Barley with altered branching enzyme activity and starch and starch containing products with an increased amylose content

ABSTRACT

Barley having a reduced level of SBEIIa activity produces grain having a high relative amylose content. The barley might additionally have reduced levels of SBEIIb activity. The barley grain of this invention can be of a non-shrunken phenotype despite a lesion in the amylopectin synthesis pathway.

This application is a divisional of U.S. Ser. No. 10/434,893, filed May9, 2003, now U.S. Pat. No. 7,521,593, issued Apr. 21, 2009, which claimspriority of Australian Application No. PS2198, filed May 9, 2002, thedisclosures of each of which are hereby incorporated herein by referenceinto this application.

FIELD OF THE INVENTION

This invention relates to a barley plant with a reduced starch branchingenzyme IIa (SBEIIa) activity in the endosperm, leading to a kernelstarch with an increase in relative amylose content. The invention alsorelates to grain and starch and food and non-food products obtainedtherefrom.

BACKGROUND OF THE INVENTION

In cereals, starch makes up approximately 45-65% of the weight of themature grain. The starch is composed of two types of molecule, amyloseand amylopectin. Amylose is an essentially linear molecule composed ofα-1,4 linked glucosidic chains, while amylopectin is highly branchedwith α-1,6 glucosidic bonds linking linear chains.

The synthesis of starch in the endosperm of higher plants is carried outby a suite of enzymes that catalyse four key steps. Firstly, ADP-glucosepyrophosphorylase activates the monomer precursor of starch through thesynthesis of ADP-glucose from G-1-P and ATP. Secondly, the activatedglucosyl donor, ADP-glucose, is transferred to the non-reducing end of apre-existing α1-4 linkage by starch synthases. Thirdly, starch branchingenzymes introduce branch points through the cleavage of a region ofα-1,4 linked glucan followed by transfer of the cleaved chain to anacceptor chain, forming a new α-1,6 linkage. Starch branching enzymesare the only enzymes that can introduce the α-1,6 linkages intoα-polyglucans and therefore play an essential role in the formation ofamylopectin. Finally, starch debranching enzymes remove some of thebranch linkages although the mechanism through which they act isunresolved (Myers et al., 2000).

While it is clear that at least these four activities are required fornormal starch granule synthesis in higher plants, multiple isoforms ofeach of the four activities are found in the endosperm of higher plantsand specific roles have been proposed for individual isoforms on thebasis of mutational analysis (Wang et al, 1998, Buleon et al., 1998) orthrough the modification of gene expression levels using transgenicapproaches (Abel et al., 1996, Jobling et al., 1999, Scwall et al.,2000). However, the precise contributions of each isoform of eachactivity to starch biosynthesis are still not known, and it is not knownwhether these contributions differ markedly between species. In thecereal endosperm, two isoforms of ADP-glucose pyrophosphorylase arepresent, one form within the amyloplast, and one form in the cytoplasm(Denyer et al., 1996, Thorbjornsen et al., 1996). Each form is composedof two subunit types. The shrunken (sh2) and brittle (bt2) mutants inmaize represent lesions in large and small subunits respectively (Girouzand Hannah, 1994). Four classes of starch synthase are found in thecereal endosperm, an isoform exclusively localised within the starchgranule, granule-bound starch synthase (GBSS), two forms that arepartitioned between the granule and the soluble fraction (SSI, Li etal., 1999a, SSII, Li et al., 1999b) and a fourth form that is entirelylocated in the soluble fraction, SSIII (Cao et al, 2000, Li et al.,1999b, Li et al, 2000). GBSS has been shown to be essential for amylosesynthesis (Shure et al., 1983), and mutations in SSII and SSIII havebeen shown to alter amylopectin structure (Gao et al, 1998, Craig etal., 1998). No mutations defining a role for SSI activity have beendescribed.

Three forms of branching enzyme are expressed in the cereal endosperm,branching enzyme I (SBEI), branching enzyme IIa (SBEIIa) and branchingenzyme IIb (SBEIIb) (Hedman and Boyer, 1982, Boyer and Preiss, 1978,Mizuno et al., 1992, Sun et al., 1997). In maize and rice, high amylosephenotypes have been shown to result from lesions in the SBEIIb gene,also known as the amylose extender (ae) gene (Boyer and Preiss, 1981,Mizuno et al., 1993; Nishi et al., 2001). In these SBEIIb mutants,endosperm starch grains showed an abnormal morphology, amylose contentwas significantly elevated, the branch frequency of the residualamylopectin was reduced and the proportion of short chains (<DP17,especially DP8-12) was lower. Moreover, the gelatinisation temperatureof the starch was increased. In addition, there was a significant poolof material that was defined as “intermediate” between amylose andamylopectin (Boyer et al., 1980, Takeda, et al., 1993b). In contrast,maize plants mutant in the SBEIIa gene due a mutator (Mu) insertionalelement and consequently lacking in SBEIIa protein expression wereindistinguishable from wild-type plants in the branching of endospermstarch (Blauth et al., 2001), although they were altered in leaf starch.Similarly, rice plants deficient in SBEIIa activity exhibited nosignificant change in the amylopectin-chain profile in endosperm(Nakamura. 2002).

In maize, the dull1 mutation causes decreased starch content andincreased amylose levels in endosperm, with the extent of the changedepended on the genetic background, and increased degree of branching inthe remaining amylopectin (Shannon and Garwood, 1984). The genecorresponding to the mutation was identified and isolated by atransposon-tagging strategy using the transposon mutator (Mu) and shownto encode the enzyme designated starch synthase II (SSII) (Gao et al.,1998). The enzyme is now recognized as a member of the SSIII family incereals. Mutant endosperm had reduced levels of SBEIIa activityassociated with the dull1 mutation. No corresponding mutation has beenreported in other cereals. It is not known if these findings arerelevant to other cereals, for example barley.

WO94/09144 suggests the use of sense and antisense genes to alter thenatural ratios of starch synthase (SS) and SBE in maize. However, nodata are presented to substantiate the proposed molecular strategies andthere is no suggestion of specifically reducing the activity of SBEIIa.

In potato, down regulation of SBEI alone causes minimal affects onstarch structure (Filpse et al., 1996), although further work identifiedsome qualitative changes (Safford et al., 1998). However, in potato thedown regulation of SBEII and SBEI in combination increased the relativeamylose content much more than the down-regulation of SBEII alone(Schwall et al., 2000).

Two types of debranching enzymes are present in higher plants and aredefined on the basis of their substrate specificities, isoamylase typedebranching enzymes, and pullulanase type debranching enzymes (Myers etal., 2000). Sugary-1 mutations in maize and rice are associated withdeficiency of both debranching enzymes (James et al., 1995, Kubo et al.,1999) however the causal mutation maps to the same location as theisoamylase-type debranching enzyme gene. In the Chlamydomonas sta-7mutant (Mouille et al., 1996), the analog of the maize sugary-1mutation, isoamylase activity alone is down regulated. Starchbiosynthesis genes that have been cloned from cereals are listed inTable 1.

Starch is widely used in the food, paper and chemical industries. Thephysical structure of starch can have an important impact on thenutritional and handling properties of starch for food or non-food orindustrial products. Certain characteristics can be taken as anindication of starch structure including the distribution of amylopectinchain length, the degree of crystallinity and the presence of forms ofcrystallinity such as the V-complex form of starch crystallinity.Amylopectin chain length may be an indicator of altered crystallinityand altered gelatinisation and is also thought to have a correlationwith reduced retrogradation of amylopectin. Additionally, variedamylopectin chain length distribution is thought to reflect organolepticproperties of food in which the starch is included in significantamounts. Reduced crystallinity of a starch may also be indicative of areduced gelatinisation temperature of starch and is thought to beassociated with enhanced organoleptic properties.

The relatively high gelatinisation temperature of most high amylosestarches is a disadvantage for certain food applications. Gelatinisationtemperature is reflective of the comminution energy required to processsuch foods. Higher temperatures are normally required to process grainor flour to manufacture foods from such grains or starches. Therefore,products having high amylose starches are generally more expensive. Inaddition, consumers may need to use longer times and higher temperaturesto prepare the manufactured foods or to make foods from flour havinghigh amylose starches. High amylose starches having reduced or normalgelatinisation temperatures would be advantageous in many foodapplications.

Starch composition, in particular the form called resistant starch, hasimportant implications for bowel health, in particular health of thelarge bowel. Accordingly, high amylose starches have been developed incertain grains such as maize for use in foods as a means of promotingbowel health. The beneficial effects of resistant starch result from theprovision of a nutrient to the large bowel wherein the intestinalmicroflora are given an energy source which is fermented to form interalia short chain fatty acids. These short chain fatty acids providenutrients for the colonocytes, enhance the uptake of certain nutrientsacross the large bowel and promote physiological activity of the colon.Generally if resistant starches or other dietary fibre is not providedthe colon is metabolically relatively inactive.

Another nutritional component of the grains and in particular of barleyis β-glucan. β-glucan consists of glucose units bonded by β (1-4) and/orβ (1-3) glycosidic linkages and are not degraded by human digestiveenzymes, making them suitable as a source of dietary fibre. β-glucanscan be partially digested by endogenous colonic bacteria whichfermentation process gives rise to short chain fatty acids(predominantly acetate, propionate and butyrate) which are beneficial tomucosal cells lining the intestine and colon (Sakata and Engelhard,1983). Ingestion of β-glucan also has the effect of increasing bile acidexcretion leading to a reduction in total serum cholesterol and lowdensity lipoproteins (LDL) with a lowering of the risk of coronarydisease. Similarly β-glucan acts by attenuating excursions inpostprandial blood glucose concentration. It is thought that theseeffects may also be based on the increase of viscosity in the contentsof the stomach and intestines.

Whilst modified starches or β glucans, for example, can be utilised infoods that provide functionality not normally afforded by unmodifiedsources, such processing has a tendency to either alter other componentsof value or carry the perception of being undesirable due to processesinvolved in modification. Therefore it is preferable to provide sourcesof constituents that can be used in unmodified form in foods.

Barley (Hordeum vulgare) is the fourth largest cereal grain cropproduced worldwide and is relatively underutilized in terms of humanconsumption aside from its use to produce alcoholic beverage. Onaverage, barley grain contains about 64% starch, 11% protein and 5%β-glucan (normally 3-6%). The remaining 20% includes moisture, fiber andother minor components.

Known variation in barley starch structure is limited relative to thevariation available in maize. Mutants in SBEIIb, corresponding to theamylose-extender phenotypes in maize or rice, have not beencharacterized in barley. The phenotype conferred by SBEIIa or SBEIIbmutations in barley is unknown. The most highly characterised mutationsare waxy and a high amylose mutation identified as AC38. High AmyloseGlacier (AC38) has relatively modest increases in amylose content to amaximum of about 45% of total starch. Double mutants with a waxyphenotype have also been constructed and analyzed (Schondelmaier et al.,1992; Fujita et al, 1999).

Other mutants of barley having high amylose starch contents have beenidentified. Chemically induced mutants in the SSIIa gene had higherlevels of amylose in kernel starch, to about 65-70% (WO 02/37955 A1).The mutants M292 and M342 also showed substantially reduced averagegrain weight as a consequence of reduced starch synthesis, from a meanweight of about 51 mg for the parent line Himalaya to 32 and 35 mg forM292 and M342, respectively. Although the mutants retained the lengthand width of the wild-type grain, they were flattened from 2.8 mmaverage thickness for Himalaya to 1.6-1.8 mm thickness and had anessentially unfilled central region, which resulted in poorer millingcharacteristics. The ratio of grain length (L) to thickness (T) wasfound to be a useful diagnostic parameter for the mutant alleles, withmutants and wild-type seeds having an L:T ratio of >3.5 and <3.5respectively. The starch content of the mutant lines was reduced from49.0% for Himalaya to 17.7 and 21.9% for M292 and M342, respectively. Itwas shown that while there was a decrease in amylose content per grainfrom 6.2 mg per caryopsis to 4.0 and 4.8 mg in M292 and M342,respectively, there was a dramatic reduction in amylopectin content percaryopsis from 18.7 in Himalaya to 1.6 and 2.9 mg in the mutants. Thisshowed that the high relative amylose level was a result of decreasedamylopectin production. Grain β-glucan levels were increased in themutants to above 10%. The starch showed reduced gelatinisationtemperatures. The SSIIa mutants had an altered distribution of SBEIIaand SBEIIb activities between the starch granule and soluble fractionsof the endosperm, however, they were essentially unaltered in the levelof these activities in the endosperm as a whole (WO 02/37955; Morell etal., 2003).

Whilst elevated amylose starches of these types are useful, a barleystarch with higher amylose contents is preferred, in particular ifassociated with improved starch synthesis and other characteristics, forexample a reduced need for post-harvest modification. Such starchproducts are also relatively resistant to digestion and bring a greaterhealth benefit.

General

Those skilled in the art will be aware that the invention describedherein is subject to variations and modifications other than thosespecifically described. It is to be understood that the inventiondescribed herein includes all such variations and modifications. Theinvention also includes all such steps, features, compositions andcompounds referred to or indicated in this specification, individuallyor collectively, and any and all combinations of any two or more of saidsteps or features.

Throughout this specification, unless the context requires otherwise theword “comprise”, and variations such as “comprises” and “comprising”,will be understood to imply the inclusion of a stated integer or step orgroup of integers or steps but not the exclusion of any other integer orstep or group of integers or steps. The present invention is not to belimited in scope by the specific embodiments described herein, which areintended for the purposes of exemplification only.Functionally-equivalent products, compositions and methods are clearlywithin the scope of the invention, as described herein.

Bibliographic details of the publications referred to by author in thisspecification are collected at the end of the description. Thereferences mentioned herein are hereby incorporated by reference intheir entirety. Reference herein to prior art, including any one or moreprior art documents, is not to be taken as an acknowledgment, orsuggestion, that said prior art is common general knowledge in Australiaor forms a part of the common general knowledge in Australia.

As used herein, the term “derived from” shall be taken to indicate thata particular integer or group of integers has originated from thespecies specified, but has not necessarily been obtained directly fromthe specified source.

The designation of nucleotide residues referred to herein are thoserecommended by the IUPAC-IUB Biochemical Nomenclature Commission,wherein A represents Adenine, C represents Cytosine, G representsGuanine, T represents Thymidine.

SUMMARY OF THE INVENTION

In a first aspect the invention might be said to reside in grainobtained from a barley plant, the barley plant having a reduced level ofSBEIIa enzyme activity in the endosperm, starch of said grain having arelative amylose content of at least 40% (w/w). The relative amylosecontent might preferably be higher than 50% or 75%, and preferably thegrain is non-shrunken.

In a second aspect the invention might be said to reside in a barleygrain comprising starch having a relative amylose content of at least75% (w/w).

In a third aspect the invention might be said to reside in flour orwholemeal obtained from the grain of the first or second aspects of theinvention, or food products incorporating such flour or wholemeal.

In a fourth aspect the invention might be said to reside in starchobtained from grain of a barley plant, the barley plant having a reducedlevel of SBEIIa enzyme activity in the endosperm, said starch beingunmodified and having a relative amylose content of at least 40% (w/w).In a specific form of the fourth aspect the barley plant additionallyhas a reduced level of SBEIIb enzyme activity in the endosperm.

In a fifth aspect the invention might be said to reside in a compositioncomprising the starch according to the fourth aspect of the inventionand another food ingredient or water.

In sixth aspect the invention might be said to reside in a compositioncomprising starch granules of barley endosperm and another foodingredient or water, wherein the starch of the starch granules comprisesat least 75% (w/w) amylose.

In a seventh aspect the invention might be said to reside in a barleyplant having a reduced level of SBEIIa enzyme activity, wherein starchin grain of the barley plant has a relative amylose content of at least40% (w/w) or preferably at least 50% or at least 75%.

In an eight aspect the invention might be said to reside in a method ofproducing a barley plant with a reduced level of SBEIIa enzyme activityin the endosperm, starch of grain of the barley plant having an amylosecontent of at least 40% (w/w), the method comprising the steps of, a)introducing a genetic variation into a parent barley plant; and b)identifying progeny plants or seed of the parent barley plant that havereduced SBEIIa activity.

In a ninth aspect the invention might be said to reside in a method ofproducing a barley plant having reduced activity of both SBEIIa andSBEIIb enzyme activities in the endosperm which comprises: a)mutagenizing seed from a plant having reduced activity of SBEIIa enzymeactivity; or b) mutagenizing seed from a plant having reduced activityof SBEIIb enzyme activity; or c) crossing a plant having reduced SEBEIIaenzyme activity with a plant having reduced SBEIIb enzyme activity; andidentifying a barley plant having reduced activity of both SBEIIa andSBEIIb.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Nucleotide sequence of the barley SBEIIa cDNA (SEQ ID No. 1).

FIG. 2. Nucleotide sequence of the barley SBEIIb cDNA (SEQ ID No. 2).

FIG. 3. Sequence of the Starch Branching Enzyme IIa gene (SEQ ID No. 3)(wSBE II-D1) from A. tauschii, corresponding to the D genome SBEIIa geneof hexaploid wheat (T. aestivum).

FIG. 4. Partial wheat SBEIIb gene sequence (SEQ ID No. 4) (wbe2bgenomic).

FIG. 5. Schematic of duplex-RNA constructs. A. The order of the geneelements used were promoter, SBEIIa or SBEIIb gene sequence (exons 1, 2and 3) in sense orientation, intron (intron 3), SBEIIa or SBEIIb genesequence (exons 1, 2, 3 and 4) in antisense orientation, andtranscription terminator/polyadenylation sequence. B. The transcript ofthe ds-SBEIIa and ds-SBEIIb genes forms a “hairpin” RNA structure with adouble-stranded region formed by hybridization between the sense andantisense sequences. The intron sequence bordered by the G and AGnucleotides is spliced out.

FIG. 6. PCR analysis of ds-SBEIIa and ds-SBEIIb transgenic lines ofbarley. The primer pairs BX17F/AR2bkpnR for SBEIIb and BX17F/AR2akpnRfor SBEIIa that amplifies the first and second fragments of respectiveconstructs which included the exons 1, 2, 3 and intron 3 (senseorientation) were used to identify positive transgenic lines. GP is forthe untransformed Golden Promise. The central lane shows molecular sizemarkers.

FIG. 7. Southern blot analysis of ds-SBEIIa and ds-SBEIIb transgeniclines of barley. A. Barley ds-SBEIIa positive transgenes as shown bySouthern blot hybridization. The expected band size is 1836 bp. B.Barley ds-SBEIIb positive transgenes as shown by Southern. The expectedband size is 1907 bp. GP is Golden Promise (negative control).

FIG. 8. Western blot analysis of ds-SBEIIa and ds-SBEIIb transgeniclines of barley. Ten T1 seeds (seeds from T0 plants) of lines IIb 4.3and IIb4.4 were analyzed for SBEIIb expression by Western blot analysisusing non-denaturing PAGE and an SBEIIb specific antibody. Lane 1 (+) isfor the positive control, variety Glacier.

FIG. 9. Western blot analysis of ds-SBEIIa and ds-SBEIIb transgeniclines of barley. T1 seeds (seeds from T0 plants) of line IIa 4.1 wereanalyzed for A. SBEIIa or B. SBEIIb expression by Western blot analysisusing non-denaturing PAGE and SBEIIa or SBEIIb specific antibodies. Thelanes on both the gels represent the same seeds. Lane 1 (+) in eachpanel is for the positive control, variety Glacier.

FIG. 10 Western blot analysis of ds-SBEIIa and ds-SBEIIb transgeniclines of barley. T1 seeds (seeds from T0 plants) of line IIb 4.1 wereanalyzed for A. SBEIIb or B. SBEIIa expression by Western blot analysisusing non-denaturing PAGE and SBEIIb or SBEIIa specific antibodies. Thelanes on both the gels represent the same seeds. The last lane (+) ineach panel is for the positive control, variety Glacier.

FIG. 11. Starch granule morphology of ds-SBEIIa transgenic barley.Starch granules from single seeds were visualized through lightmicroscopy for both ds-SBEIIa and ds-SBEIIb transgenic seeds. FIG. 11A,seed with wild type SBEIIa expression (line IIa4.2.3). FIG. 11B, seedwhich lack SBEIIa expression (line IIa4.2.5). A significantmorphological alteration was observed in starch from seeds lackingSBEIIa but not for SBEIIb.

FIG. 12. Scanning electron microscopy (SEM) of starch granules. A.wild-type starch granules (line IIa 4.2.3), B. and C. from a ds-SBEIIatransgenic endosperm (line IIa 4.2.5). Starch granules from ds-SBEIIb(SBEIIb inactivated) seed did not appear to be morphologically alteredcompared to wild-type

DETAILED DESCRIPTION OF THE INVENTION Alteration of SBEIIa in Barley

The invention is based on the finding that a reduction in SBEIIaactivity in barley endosperm results in modified starch production,particularly high amylose accumulation in the barley grain. Thisunexpected result is in contrast to the findings in maize and rice wheremutation in SBEIIa did not alter the amylopectin profile (Blauth et al.,20001, Nakamura, 2000). Preferably, there is an alteration in one ormore additional starch biosynthetic enzyme activities, and morepreferably a reduction in SBEIIb as well as SBEIIa. Preferably also thegrain of this barley plant is non-shrunken.

Method of Producing a Barley Plant

In an aspect, the invention provides a method of reducing starchbranching enzyme IIa (SBEIIa) activity in the endosperm of barley. Thereduction in activity may be by at least 40% or perhaps preferably by atleast 50% compared to the level of activity in the endosperm ofunmodified (control) barley, more preferably by at least 75%, and evenmore preferably by at least 90% or 95%. The method may comprise thealteration of the expression of the SBEIIa gene of barley, or it maycomprise the mutation of the SBEIIa gene in barley, whereby the SBEIIaactivity in endosperm is reduced.

The method may comprise the step of determining the activity of SBEIIain barley endosperm, preferably by measuring the level of the protein,for example by immunodetection, or the level of its corresponding mRNAby methods well known in the art, such as Northern blot hybridizationanalysis or reverse transcription polymerase chain reaction (RT-PCR).The method may further comprise the step of selecting or screening for abarley plant or grain having reduced SBEIIa activity in its endosperm.The selection step may be based on the reduced level of the SBEIIaactivity or protein, or it may be based on the phenotype of the grain ofthe barley plant such as increased amylose content or decreasedamylopectin content or a visual phenotype, for example shrunken grain.

SBE activity may be measured by enzyme assay, for example by thephosphorylase stimulation assay (Boyer and Preiss, 1978). This assaymeasures the stimulation by SBE of the incorporation of glucose1-phosphate into methanol-insoluble polymer (α-D-glucan) byphosphorylase a. SBE activity can be measured by the iodine stain assay,which measures the decrease in the absorbance of a glucan-polyiodinecomplex resulting from branching of glucan polymers. SBE activity canalso be assayed by the branch linkage assay which measures thegeneration of reducing ends from reduced amylose as substrate, followingisoamylase digestion (Takeda et al., 1993a). Preferably, the activity ismeasured in the absence of SBEI or SBEIIb activity. Isoforms of SBE showdifferent substrate specificities, for example SBEI exhibits higheractivity in branching amylose, while SBEIIa and SBEIIb show higher ratesof branching with an amylopectin substrate. The isoforms may also bedistinguished on the basis of the length of the glucan chain that istransferred.

In a further aspect, the invention provides a method of reducing theactivity of multiple starch biosynthesis enzymatic activities in barleyendosperm, wherein one of the activities is SBEIIa. Preferably, theactivities of both SBEIIa and SBEIIb are reduced, and even morepreferably SBEI activity is also reduced. Other starch biosynthesisenzymatic activities that may be reduced in combination with SBEIIa are:SSI, SSII, SSIII. Starch debranching enzymes may also be altered, forexample the activity of isoamylase or pullulanase. In a furtherembodiment, the activities of starch biosynthesis enzymatic activitiesmay be altered in the plant in tissues other than endosperm, for examplethe activity of SBEI or SBEII may be increased in leaves to compensatefor some loss of activity caused by a transgene encoding anSBEIIa-inhibitory molecule intended primarily for expression in theendosperm. Alternatively, starch synthesis may be further improved bythe overexpression of one or more starch biosynthetic enzymes incombination with a reduction in SBEIIa. Genes encoding such enzymes maybe from any of a variety of sources, for example from bacterial or othersources other than barley, and may be modified to alter the catalyticproperties, for example alteration of the temperature dependence of theenzymes (WO94/09144).

In a further aspect, the invention provides a method of increasing thelevel of amylose (as a percentage of starch) in barley grain, comprisingthe step of reducing the activity of SBEIIa in barley endosperm. Theamylose content is preferably at least 50%, more preferably at least 60%and even more preferably at least 65, 75% or 70%. In further preferredembodiments of the invention, the method provides for amylose contentsof at least 80% or 90%, as exemplified herein.

The high amylose phenotype may be achieved by partial or full disruptionto the expression of the SBEIIa gene, or the SBEIIa and SBEIIb genes.The extent to which the gene is inhibited will in some degree determinethe characteristics of the starch made in the barley grain. Any of arange of gel electrophoresis techniques carried out on the proteinsextracted from the modified barley endosperm will reveal the nature andextent of modification to the SBEIIa and/or SBEIIb activity.Modification may occur as a reduction in SBEIIa and/or SBEIIb activity,complete abolition of enzyme activity, or an alteration in thedistribution of the SBEIIb or other enzymes within the endosperm. Tocarry out these tests, starch may be extracted from the barley endospermand the proteins therein analyzed, for example as outlined in Rahman etal, 1995. Techniques well known in the art such as SDS-PAGE andimmunoblotting are carried out on the soluble and the starch granulefractions and identify the plants or grain where modifications haveoccurred to the SBEIIa and/or SBEIIb enzymes.

Barley Plants

In a further aspect, the invention provides a barley (Hordeum vulgare)plant with a reduced level of SBEIIa activity in the endosperm during atleast some of the development of the grain, the barley plant beingcapable of bearing grain having starch comprising a high relativeamylose content. Preferably, the level of SBEIIa is reduced in theendosperm by at least 50%, more preferably by at least 75% and mostpreferably by at least 90% or 95% compared to the wild-type. The term“wild-type” has its normal meaning in the field of genetics and includesbarley cultivars or genotypes which are not modified as taught herein.

The invention also provides progeny plants and grain which have thedesired characteristics of the parent.

The invention also encompasses barley plants that have altered SBEIIb orother starch biosynthetic enzyme activities in addition to reducedSBEIIa activity. Plants having reduced SBEIIa and SBEIIb activities maybe produced by crossing a plant reduced for SBEIIa with a plant reducedfor SBEIIb, or by introducing a transgene encoding a molecule thatinhibits expression of both SBEIIa and SBEIIb genes. The invention alsoencompasses the mutation(s) in other genetic backgrounds. The originalaltered (mutant) plants may be crossed with plants containing a moredesirable genetic background. After the initial crossing, a suitablenumber of backcrosses may be carried out to remove the less desirablebackground. The desired genetic background may include a suitablecombination of genes providing commercial yield and othercharacteristics such as agronomic performance, abiotic stress resistanceor hull-less grain. The genetic background might also include otheraltered starch biosynthesis or modification genes, for example theamylose extender phenotype or the amo1 mutation in High Amylose Glacierbarley (gene unknown), the waxy mutation (found for example in theWaxiro variety), the mutant gene in the high amylose variety MK6827(available from the USDA ARS National Small Grain Germplasm ResearchFacility Aberdeen, Id. 831290 USA) or the high amylose varieties M292and M342 (mutation in the SSIIa gene) or modifier genes. Additionally itmay be desirable to combine other double and triple mutations withcombinations of the above lines and in crosses with other barley linesthat have a shrunken endosperm where the causal gene is not known.

Grain

The invention also provides barley grain comprising an altered starchcompared to wild-type. The altered starch is at least partly aconsequence of reduced SBEIIa activity during development of endospermof the barley grain. The grain comprises increased amylose levels as apercentage of total starch and a reduced amylopectin content compared towild-type, which has approximately 25% amylose and 75% amylopectin.Preferably, both SBEIIa and SBEIIb activities are reduced duringdevelopment of the endosperm. Even more preferably, the activity of SBEIis also reduced. The amylose levels, as measured by methods wellunderstood in the art, are preferable at least 50% of the total starch,more preferably at least 60% and even more preferably at least 65%, 70%,75%, 80% or 90%. Increased amylose levels may be evidenced by abnormalstarch granule morphology or loss of birefringence of the granules whenobserved under a light microscope or other methods. Preferably theamylose level is measured by an iodometric method, which may bespectrophotometric (for example, Morrison and Laignelet, 1983) or byhigh-performance liquid chromatography (HPLC, for example, Batey andCurtin, 1996).

The grain of the barley plant may have an elevated level of β glucan,which may be associated with increased carbon flow into this polymerrather than into amylopectin synthesis. Alternatively, the grain mayhave normal levels of β glucan, for example in the range 3.0-6.0% of themature grain weight. More preferably, the grain comprises both elevatedamylose and normal levels of β glucan. Such a combination is unexpected,based on the composition of starch in grain from SSIIa mutant barley (WO02/37955). The grain may comprise starch that has altered gelatinisationtemperatures and/or altered swelling characteristics during andfollowing gelatinisation. The grain also, preferably, has a non-shrunkenphenotype.

The invention also provides flour or meal produced from the grain. Thesemay be unprocessed or processed, for example by fractionation orbleaching. The invention further provides barley grain useful for foodproduction obtained from a barley plant having an altered level of aSBEIIa activity in the endosperm, starch of said grain having a highamylose content and a reduced amylopectin content. Additionally theinvention encompasses grain that has been processed in other ways, sothat the grain may have been milled, ground, pearled, kibbled orcracked.

Starch

In another aspect, the invention provides starch obtained from the grainof the barley plant as described above, the plant having a reduced levelof SBEIIa activity in the endosperm, the starch having a high amylosecontent and a reduced amylopectin content. Preferably both SBEIIa andSBEIIb activities are reduced, and more preferably the activity of SBEIis also reduced. In another aspect, the invention provides starchobtained from the grain of the barley plant, comprising at least 50%amylose, preferably at least 60% amylose, and even more preferably atleast 65%, 70%, 75%, 80% or 90% amylose.

Purified starch may be obtained from grain by a milling process, forexample a wet milling process, which involves the separation of thestarch from protein, oil and fibre. The initial product of the millingprocess is a mixture or composition of starch granules, and theinvention therefore encompasses such granules. The starch of thegranules comprises at least 50%, preferably 70%, 75% or 80% amylose.

The starch may comprise an elevated level of resistant starch, with analtered structure indicated by specific physical characteristicsincluding one or more of the group consisting of physicalinaccessibility to digestive enzymes which may be by reason of having ahigh β-glucan content, altered starch granule morphology, the presenceof appreciable starch associated lipid, altered crystallinity, andaltered amylopectin chain length distribution. The high amylose contentalso contributes to the level of resistant starch.

The invention also provides starch from grain of the exemplified barleyplant comprising increased amounts of dietary fibre, preferably incombination with the elevated level of resistant starch. This increaseis also at least in part a result of the high relative level of amylose.

Methods of Reducing Gene Activity: Transgenes

The activity of SBEIIa and optionally other starch biosynthesis ormodification genes are preferably altered by introducing a geneticvariation into the plant which might be by means of the introduction ofa transgene into the barley plant. A “genetic variation” means anyalteration in the genome which, in this context, affects the activity ofSBEIIa, and includes mutations such as point mutations, substitutions,inversions, translocations and preferably deletions, as well asintroduction of transgenes. A “transgene” as referred to herein has thenormal meaning in the art of biotechnology and includes a geneticsequence which has been produced or altered by recombinant DNA or RNAtechnology and which has been introduced into the organism or cell ofinterest. The transgene may include genetic sequence derived from theorganism or cell, for example an antisense sequence. The transgenetypically includes an exogenous nucleic acid which is not derived fromsaid organism or cell. “Transgenic” refers to the organism or cellcontaining a transgene. “Non-transgenic” refers to the absence of anytransgene in the genome. A transgene is preferably integrated into thegenome of the organism or cell, for stable inheritance.

The method of reducing SBEIIa activity may comprise the step ofintroducing a transgene into a regenerable cell of barley andregenerating a transgenic barley plant from the transformed cell. Thebranching enzymes involved in synthesis of amylopectin include SBEI,SBEIIa and SBEIIb and the invention encompasses a reduced expression ofSBEIIa alone or in combination with alteration of SBEIIb or SBEIexpression. Therefore, the transgene(s) may inactivate more than one ofthese genes. Moreover, the inactivation of SBEIIb and/or SBEI may bedirect, in that the transgene (e.g. encoding duplex RNA, antisense, orribozyme RNA, see below) directly targets the SBEIIb or SBEI geneexpression, or it may indirectly result in the alteration in theexpression of SBEIIb or SBEI. For example, the transgene RNA may targetonly the SBEIIa gene/RNA in terms of sequence identity or basepairingbut also result in reduction of SBEIIb or SBEI by altering proteinstability or distribution. Additionally forms of the present inventionreside in the combination of an altered activity of SBEIIa and analteration of one or more other amylopectin synthesis enzymes, whichenzymes may include SSI, SSII, SSIII, and debranching enzymes such asisoamylase or pullulanase. Expression of any or all of these may bealtered by introduction of a transgene.

Several DNA sequences are known for amylopectin synthesis genes inbarley, any of which can be the basis for designing transgenes forinactivation of the genes in barley. These include SBEIIa (GenBankaccession numbers AF064562 and AF064560), SBEIIb (GenBank accessionnumbers AF064563 and AF064561). Homologs of the SBEI gene of barley canbe isolated by utilising sequences based on DNA sequences from othergrains, for example by techniques such as those set out in WO99/14314 toLi et al., for Triticum. The Triticum tauschii sequence for SBEI, whichis highly homologous to the wheat D genome SBEI gene and has a highdegree of similarity to the barley gene, can be found in publishedPatent specification WO 99/14314 or referenced cited therein, whichdocument is incorporated herein by reference. The sequence for SBEI ofwheat can be accessed in the GenBank database under accession numberAF076679. Homologues of other amylopectin synthesising genes from wheator other closely related species can also be used to modify geneexpression levels in barley. Such genes or fragments thereof can beobtained by methods well known in the art, including PCR amplificationor hybridization to labeled probes.

“Stringent hybridization conditions” as used herein means thathybridization will generally occur if there is at least 90% andpreferably at least 95% sequence identity between the probe and thetarget sequence. Examples of stringent hybridization conditions areovernight incubation in a solution comprising 50% formamide, 5×SSC(1×SSC=150 mM NaCl, 15 mM trisodium citrate), 50 mM sodium phosphate (pH7.6), 5×Denhardt's solution, 10% dextran sulfate, and 20 μg/ml denaturedsheared carrier DNA such as salmon sperm DNA, followed by washing thehybridization support in 0.1×SSC at approximately 65° C. Otherhybridization and wash conditions are well known and are exemplified inSambrook et al, Molecular Cloning: A Laboratory Manual, Second Edition,Cold Spring Harbor, N.Y. (1989), particularly chapter 11.

The region(s) of the homologues used in preparing the transgeneconstruct should have at least 85% identity to the corresponding barleygene, preferably at least 90% and even more preferably 95-100% identityin the appropriate region. It is also preferred that the transgenespecifically target the amylopectin synthesis genes expressed in theendosperm of barley and have less or minimal effect on amylopectinsynthesis elsewhere in the plant. This may be achieved by use ofsuitable regulatory sequences such as endosperm-specific promoters inthe transgene.

Antisense

Known genetic engineering or transgenic approaches to altering, inparticular specifically reducing, gene activity in plants are well knownin the art. These methods of introducing genetic variation into thebarley plant include the expression of a suitable antisense moleculethat is complementary to the RNA of the target gene and can hybridizewith it. Antisense molecules are thought to interfere with thetranslation or processing or stability of the mRNA of the target gene,thereby inactivating its expression. Methods of devising antisensesequences are well known in the art and examples of these are can befound in U.S. Pat. No. 5,190,131, European patent specification0467349-A1, European patent specification 0223399-A1 and European patentspecification 0240208, which are incorporated herein by reference. Theuse of antisense techniques in plants has been reviewed by Bourque(1995) and Senior (1998). Bourque lists a large number of examples ofhow antisense sequences have been utilized in plant systems as a methodof gene inactivation. She also states that attaining 100% inhibition ofany enzyme activity may not be necessary as partial inhibition will morethan likely result in measurable change in the system. Senior (1998)states that antisense methods are now a very well established techniquefor manipulating gene expression.

Antisense molecules for barley SBEIIa, SBEIIb, SBEI or other amylopectinbiosynthesis genes can be based on the barley mRNA sequences or based onhomologies with DNA or mRNA sequences derived from other species, forexample wheat. These antisense sequences may correspond to thestructural genes or for sequences that effect control over the geneexpression or splicing event. For example, the antisense sequence maycorrespond to the targeted coding region of the barley SBEIIa or othergene, or the 5′-untranslated region (UTR) or the 3′-UTR or combinationof these. It may be complementary in part to intron sequences, which maybe spliced out during or after transcription, preferably only to exonsequences of the target gene. In view of the generally greaterdivergence of the UTRs, targeting these regions provides greaterspecificity of gene inhibition. The length of the antisense sequenceshould be at least 19 contiguous nucleotides, preferably at least 50nucleotides, and more preferably at least 100, 200, 500 or 1000nucleotides. The full-length sequence complementary to the entire genetranscript may be used. The length is most preferably 100-2000nucleotides. The degree of homology of the antisense sequence to thetargeted transcript should be at least 85%, preferably at least 90% andmore preferably 95-100%. The antisense RNA molecule may of coursecomprise unrelated sequences which may function to stabilize themolecule.

Cosuppression

Another molecular biological approach that may be used isco-suppression. The mechanism of co-suppression is not well understoodbut is thought to involve post-transcriptional gene silencing (PTGS) andin that regard may be very similar to many examples of antisensesuppression. It involves introducing an extra copy of a gene or afragment thereof into a plant in the sense orientation with respect to apromoter for its expression. The size of the sense fragment, itscorrespondence to target gene regions, and its degree of homology to thetarget gene are as for the antisense sequences described above. In someinstances the additional copy of the gene sequence interferes with theexpression of the target plant gene. Reference is made to Patentspecification WO 97/20936 and European patent specification 0465572 formethods of implementing co-suppression approaches.

Double Stranded RNA-Mediated Gene Silencing

A further method that might be employed to introduce genetic variationinto the barley plant is duplex or double stranded RNA mediated genesilencing. This method also involves PTGS. In this method a DNA isintroduced that directs the synthesis of an at least partly doublestranded RNA product(s). The DNA therefore comprises both sense andantisense sequences that, when transcribed into RNA, can hybridize toform the double-stranded RNA region. In a preferred embodiment, thesense and antisense sequences are separated by a spacer region thatcomprises an intron which, when transcribed into RNA, is spliced out.This arrangement has been shown to result in a higher efficiency of genesilencing. The double-stranded region may comprise one or two RNAmolecules, transcribed from either one DNA region or two. The presenceof the double stranded molecule triggers a response from an endogenousplant system that destroys both the double stranded RNA and also thehomologous RNA transcript from the target plant gene, efficientlyreducing or eliminating the activity of the target gene. Reference ismade to Australian Patent specification 99/292514-A and Patentspecification WO 99/53050 for methods of implementing this technique.The length of the sense and antisense sequences that hybridise shouldeach be at least 19 contiguous nucleotides, preferably at least 50nucleotides, and more preferably at least 100, 200, 500 or 1000nucleotides. The full-length sequence corresponding to the entire genetranscript may be used. The lengths are most preferably 100-2000nucleotides. The degree of homology of the sense and antisense sequencesto the targeted transcript should be at least 85%, preferably at least90% and more preferably 95-100%. The RNA molecule may of course compriseunrelated sequences which may function to stabilize the molecule.

Ribozymes

Ribozymes may be used to introduce the genetic variation responsible forinactivation of the desired gene expression in barley. Ribozymes are RNAmolecules with enzymatic or catalytic function that can cleave other RNAmolecules at specific sites defined by one or often two hybridizingsequences. The cleavage of the RNA inactivates the expression of thetarget gene. The ribozymes may also act as an antisense molecule, whichmay contribute to the gene inactivation. The ribozymes contain one ormore catalytic domains, preferably of the hammerhead or hairpin type,between the hybridizing sequences. Other ribozyme motifs may be usedincluding RNAseP, Group I or II introns, and hepatitis delta virustypes. Reference is made to European patent specification 0321201 andU.S. Pat. No. 6,221,661. The use of ribozymes to inactivate genes intransgenic plants has been demonstrated, for example by Wegener et al(1994).

Genetic Constructs/Vectors

The invention also provides isolated nucleic acid molecules includingRNA and preferably DNA which encode the gene-inhibiting molecule.Preferably, the nucleic acid molecules encode the antisense, sense(co-suppression), double-stranded RNA or ribozyme molecules targetingthe barley SBEIIa gene sequence and effective in inactivating itsexpression in endosperm of barley grain. The invention also providesgenetic constructs comprising the isolated nucleic acid molecule,comprising one or more regulatory elements such as promoters, enhancersand transcription termination or polyadenylation sequences. Suchelements are well known in the art. The genetic constructs may alsocomprise intron sequences which aid expression of the transgene inplants, particularly in monocotyledonous plants such as barley. The term“intron” is used in its normal sense as meaning a genetic segment thatis transcribed but does not encode protein and which is spliced out ofan RNA before translation. Introns may be incorporated in a 5′-UTR or acoding region if the transgene encodes a translated product, or anywherein the transcribed region if it does not.

The invention further provides vectors, for example plasmid vectors,comprising the genetic constructs. The term “vector” includes anexpression vector, being capable of in vitro or in vivo expression, anda transformation vector, capable of being transferred from one cell ororganism to another. The vectors comprise sequences that provide forreplication in cells, for example in prokaryotic cells such as E. colior Agrobacterium. Preferably, the vector is a binary vector comprising aT-DNA sequence, defined by at least one T-DNA border sequence, that canbe introduced into barley cells. The invention further provides cellscomprising the vectors, for example Agrobacterium or barley cells whichmay be regenerable cells such as the cells of the scutellum of immatureembryos. Alternatively, the cells may be transformed barley cellscomprising the transgene.

Promoters/Terminators

The transgene or other genetic construct of the invention may include atranscriptional initiation region (promoter) which may provide forregulated or constitutive expression in the endosperm of barley. Thepromoter may be tissue specific, conferring expression selectively orexclusively in the endosperm. The promoter may be selected from eitherendosperm-specific (such as High Molecular Weight Glutenin promoter, thewheat SSI promoter, wheat SBEII promoter, wheat GBSS promoter) orpromoters not specific for the endosperm (such as ubiquitin promoter orCaMV35S or enhanced 35S promoters). The promoter may be modulated byfactors such as temperature, light or stress. Ordinarily, the promoterwould be provided 5′ of the genetic sequence to be expressed. Theconstruct may also contain other elements that enhance transcriptionsuch as the nos 3′ or the ocs 3′ polyadenylation regions ortranscription terminators. The regions of DNA illustrated will beincorporated into vectors containing suitable selectable marker genesequences and other elements, or into vectors that are co-transformedwith vectors containing these sequences.

Transformation Methods for Barley

Methods for transformation of monocotyledonous plants such as barley forintroducing genetic variation into the plant by introduction of anexogenous nucleic acid and for regeneration of plants from protoplastsor immature plant embryos are well known in the art, see for example,Wan and Lemaux (1994), Tingay et al (1997), Canadian Patent Application2092588 by Nehra, Australian Patent Application No 61781/94 by NationalResearch Council of Canada, Australian Patent No 667939 by Japan TobaccoInc., International Patent Application PCT/US97/10621 by MonsantoCompany, U.S. Pat. No. 5,589,617, and other methods are set out inPatent specification WO99/14314. Vectors carrying the desired nucleotidesequence or genetic construct and a selectable marker may be introducedinto regenerable barley cells of tissue cultured plants or explants, orsuitable plant systems such as protoplasts. The selectable marker genemay provide antibiotic or herbicide resistance to the barley cells, orallow the utilization of substrates such as mannose. The selectablemarker preferably confers hygromycin resistance to the barley cells. Theregenerable barley cells are preferably from the scutellum of immatureembryos, mature embryos, callus derived from these, or the meristematictissue.

The transformed plant may contain a selectable marker gene, or such genemay be removed during or after regeneration, for example by excision ofthe selectable marker gene out of the genome or by segregation of theselectable marker gene away from the SBEIIa-inhibiting transgene.

Plants where the transgene or mutation has been integrated into achromosome can be screened for by, for example, using a suitable nucleicacid probe specific for the transgene or phenotypic observation. Any ofseveral methods may be employed to determine the presence of atransformed plant. For example, polymerase chain reaction (PCR) may beused to amplify sequences that are unique to the transformed plant, withdetection of the amplified products by gel electrophoresis or othermethods. DNA may be extracted from the plants using conventional methodsand the PCR reaction carried out using primers that will distinguish thetransformed and non-transformed plants. For example, primers may bedesigned that will amplify a region of DNA from the transformationvector reading into the construct and the reverse primer designed fromthe gene of interest. These primers will only amplify a fragment if theplant has been successfully transformed. An alternative method toconfirm a positive transformant is by Southern blot hybridization, wellknown in the art. Plants which are transformed or mutant may also beidentified i.e. distinguished from non-transformed or wild-type plantsby their phenotype, for example conferred by the presence of aselectable marker gene, or the presence of a particular protein byimmunological methods, or by the absence of a protein, for example thatabsence of the SBEIIa protein in the endosperm as detected by ELISAassay. An indication used in screening such plants might also be byobservation of the phenotypic traits of the grain, for example by visualinspection or measurement of shrunken grain, or testing for elevatedamylose content, or checking microscopically for the presence ofbirefringence.

Mutation

Introduction of the genetic variation leading to reduced activity of theSBEIIa enzyme or other enzyme in the barley endosperm may also beachieved by the appropriate mutations within the respective gene orregulatory sequences of the gene. The extent to which the gene isinhibited will to some degree determine the characteristics of thestarch made. The mutations may be truncation or null mutants and theseare known to have a significant impact on: the nature of the starch,however an altered amylopectin structure will also result from a leakymutant that sufficiently reduces amylopectin synthesis enzyme activityto provide the characteristic of interest in the starch or grain ofbarley. Other chromosomal rearrangements may also be effective and thesemight include deletions, inversions, duplication or point mutations.

Mutagenesis can be achieved by chemical or radiation means, for exampleEMS or sodium azide (Zwar and Chandler, 1995) treatment of seed, orgamma irradiation. Isolation of mutants may be achieved by screeningmutagenized plants or seed. For example, a mutagenized population ofbarley may be screened for high amylose content in the grain and/orlonger than normal amylopectin chain length distribution, or loss of theSBEIIa protein by ELISA, or for altered grain morphology (Green et al.,1997). Screening is preferably done in a barley genotype which alreadylacks one of the SBE activities, for example in a SBEIIb-negativebackground. Such mutations may then be introduced into desirable geneticbackgrounds by crossing the mutant with a plant of the desired geneticbackground and performing a suitable number of backcrosses to cross outthe originally undesired parent background.

Mutations in the genes encoding the SBEIIa or other enzymes involved inamylopectin synthesis will generally cause increased relative amylosecontent. The amount of amylose per individual grain may be increased asa consequence of diverted carbon flow from amylopectin to amylose, or itmay be decreased if there is a significant decrease in starch productionper grain. In either case, the relative level of amylose as a percentageof starch increases.

Suitable for Food Production

In another aspect, the invention provides barley that is useful for foodproduction, the grain being obtained from a barley plant having areduced level of SBEIIa activity in the endosperm of developing grain,starch of said grain having a relatively high amylose content and areduced amylopectin content. The barley plant of the present inventionis preferably one having grain that is useful for food production and inparticular for commercial food production. Such food production mightinclude the making of flour or other products that might be aningredient in commercial food production.

The desired genetic background of the barley will include considerationsof agronomic yield and other characteristics. Such characteristics mightinclude whether it is desired to have a winter or spring type of barley,agronomic performance, disease resistance and abiotic stress resistance.In Australia one might want to cross into barley cultivars such asSloop, Schooner, Chebec, Franklin, Arapiles, Tantangara, Galleon,Gairdner or Picola. The examples provided are specific for an Australianproduction region, and other varieties will be suited for other growingregions. It is preferred that the barley variety of the inventionprovide a yield not less than 80% of the corresponding wild-type varietyin at least some growing regions, more preferably not less than 90% andeven more preferably not less than 95%. The yield can readily bemeasured in controlled field trials. It is also preferred that thebarley plants are hull-less or “naked”, because the presence of husks onbarley grains introduces greater difficulty in processing the grain.

The starch content of the grain should be at least about 12% (w/w) or15%, preferably at least 25%, more preferably at least 35% and even morepreferably near to the wild-type levels of 45-50% (w/w). Lower starchcontents than wild-type are likely a consequence of reduced amylopectinlevels. The grain may still be useful for commercial food productionbecause of the relatively high value of the high amylose products. Otherdesirable characteristics include the capacity to mill the grain. Whilstpearled barley may be produced from most forms of grain, certainconfigurations of grain are particularly resistant to milling. Anothercharacteristic that might have an impact on commercial usefulness ofgrain is the coloration of the product produced from the grain. Wherethe husk or other portion of the grain exhibits significant colorationother than the normal this may limit its commercial applications toniche applications such as being a component of bread containingcoloured whole or kibbled grains. Typically in barley the significantcoloration is purple, and that may be a bright and strong colorationwhich is highly undesirable in most food products. Another aspect thatmight make a barley plant of higher value is the degree of starchextraction from the grain, the higher extraction rates being moreuseful. Grain shape is also another feature the can impact on thecommercial usefulness of a plant, thus grain shape can have an impact onthe ease or otherwise with which the grain can be milled. For example,the barley grain of the high amylose MK6827 plant has a very elongatedgrain morphology which makes it difficult to mill and process. Aconvenient measure of this elongate shape and associated usefulness isthe ratio of the length of the grain to the thickness of the grain (L/Tratio). This ratio is often dictated by the nature of the starch. It ispreferred that this ratio is less than 5.5, more preferably ranging fromabout 4 to about 5, and most preferably less than 3.5 on average.

A fuller grain may be desirable in terms of achieving greater yields andcertain benefits of the invention might be achieved, such as theproduction of starch with high levels of amylose, or in the alternativestarch with altered chain length distributions. Thus the grainpreferably has a non-shrunken phenotype. Other aspects of the inventionmay, however, be better achieved by a grain that is less filled. Thusthe proportion of aleurone layer or germ to starch may be higher in lessfilled grain, thereby providing for a barley flour or other product thatis higher in the beneficial constituents of the aleurone layer. The highaleurone layer product might thus be higher in certain vitamins such asfolate, or it might be higher in certain minerals such as calcium, andthat combined with higher resistant starch levels and/or higher β glucanlevels might provide synergistic effects such as providing for enhanceduptake of minerals in the large bowel.

In order to maximise the amount of amylose, it may be desirable for thebarley plant to also have other phenotypic characteristics in additionto a reduced activity of SBEIIa. The genetic background might thereforeinclude additionally the amo1 mutation in AC38 (causal gene unknown) orthe waxy mutation (found for example in the Waxiro variety).Additionally it might be desired to make double mutations in otherbarley mutants available with shrunken endosperms where the causal geneis not known.

Starch is readily isolated from barley grain using standard methods, forexample the method of Schulman et al. (1991). On an industrial scale,wet or dry milling can be used. The starch obtained from the grain ofbarley plant of the invention has a high relative amylose content.Barley plants having at least 35-45% amylose in the starch areconsidered to be high amylose. The present invention however providesfor barley with an amylose content that is greater than 50% (w/w),preferably at least 60%, and more preferably at least 70%, 75%, 80% or90%.

It will be understood that the relative level of amylose referred to isin relation to total starch content, and thus the remainder of thestarch might be predominantly of an intermediate type of starch or itmight be predominantly amylopectin or a mixture of both.

β Glucan

It is known that there is a wide variation in β glucan levels in barleyin the range of about 4% to about 18% by weight of the barley, but moretypically from 4% to about 8% (for example, Izydorcyk et al., 2000).Enhanced barley strains have been developed, for example, which havebetween about 15% and about 18% by weight β-glucan but has a waxyphenotype.

The levels of β glucan contemplated by this invention may depend on thegenetic background in which the amylopectin synthesis enzyme activity,including SBEIIa, is reduced. The exemplified embodiment showsrelatively normal β glucan synthesis, however other forms of theinvention may contemplate an elevated relative level of β glucan. Thusthe grain of the barley plant preferably has a β glucan content ofbetween about 3 to 6% (w/w) of total non-hulled grain weight. Otherforms of the invention may however exhibit β-glucan content of greaterthan 6% or higher, for example, 6-8%. Levels of β glucan in a waxymutant has been measured as being as high as 15 to 18%, for examplevariety Prowashonupana, sold commercially under the name Sustagrain™,(ConAgra™ Specially Grain Products Company, Omaha, Neb. USA) and thepresent invention may contemplate levels as high, or higher, than that.

Gelatinisation Temperature

Gelatinisation is the collapse (disruption) of molecular order withinthe starch granule with concomitant and irreversible changes inproperties such as granular swelling, crystallite melting, loss ofbirefringence, viscosity development and starch solubilisation. Highamylose starch from ae (amylose extender) mutants of maize showed ahigher gelatinisation temperature than normal maize (Fuwa et al., 1999,Krueger et al., 1987). On the other hand, starch from barley sex6mutants that lack starch synthase IIa activity had lower gelatinisationtemperatures and the enthalpy for the gelatinisation peak was reducedwhen compared to that from control plants (Morell et al., 2003).

In another aspect of the invention, the starch may have an alteredgelatinisation temperature as measured by differential scanningcalorimetry. This may be either increased or reduced compared to starchfrom wild-type plants. The altered gelatinisation temperature may be inaddition to the relatively high amylose content. Where thegelatinisation temperature is reduced, it may be reduced when comparedto starch produced by other barley varieties with elevated amylosecontent, or it may be reduced when compared with starch produced frombarley with normal levels of amylose. Alternative forms of the inventioncontemplate gelatinisation temperatures that are unaltered or are raisedrelative to wild-type barley starch. The gelatinisation temperature ofwild-type barley starch is typically about 56° C. for the temperature ofthe first peak as measured by differential scanning calorimetry.

Swelling Volume

The starch may also be characterized by its swelling rate in heatedexcess water compared to wild-type starch. Swelling volume is typicallymeasured by mixing either a starch or flour with excess water andheating to elevated temperatures, typically greater than 90° C. Thesample is then collected by centrifugation and the swelling volume isexpressed as the mass of the sedimented material divided by the dryweight of the sample. A low swelling characteristic is useful where itis desired to increase the starch content of a food preparation, inparticular a hydrated food preparation.

Crystallinity

The starch structure of the barley of selected forms of the presentinvention may also differ in that the degree of crystallinity is reducedcompared to normal starch isolated from barley. The reducedcrystallinity of a starch is also thought to be associated with enhanceorganoleptic properties and contributes to a smoother mouth feel. Thusthe starch may additionally exhibit reduced crystallinity resulting fromreduced levels of activity of one or more amylopectin synthesis enzymesCrystallinity is typically investigated by X-ray crystallography.

Distribution of Amylopectin Chain Lengths

One measurement of an altered amylopectin structure is the distributionof chain lengths, or the degree of polymerization, of the starch. Thechain length distribution may be determined by usingfluorophore-assisted carbohydrate electrophoresis (FACE) followingisoamylase de-branching. The amylopectin of the starch of the inventionmay have a distribution of chain length in the range from 5 to 60 thatis greater than the distribution of starch from wild-type plants upondebranching. Starch with longer chain lengths will also have acommensurate decrease in frequency of branching. Thus the starch mayalso have a distribution of longer amylopectin chain lengths in theamylopectin still present.

Food Characteristics

Starch is the major source of carbohydrate in the human diet, and thegrain of the invention and products derived from it can be used toprepare food. The food may be consumed by man or animals, for example inlivestock production or in pet-food. The grain derived from the alteredbarley plant can readily be used in food processing procedures, andtherefore the invention includes milled, ground, kibbled, pearled orrolled grain or products obtained from the processed or whole grain ofthe barley plant referred to above, including flour. These products maybe then used in various food products, for example farinaceous productssuch as breads, cakes, biscuits and the like, or food additives such asthickeners or binding agents, or to make malted or other barley drinks,noodles and quick soups. The grain or products derived from the grain ofthe invention are particularly desired in breakfast cereals. The highamylose starches of the invention can also be used to form high strengthgels which are useful in the confectionery industry, or allow lowermolding and curing times. They may also be used as a coating, forexample to reduce oil absorption in deep-fried potato or other foods.

Dietary Fibre

Dietary fibre, in this specification, is the carbohydrate andcarbohydrate digestion products that are not absorbed in the smallintestine of healthy humans but enter the large bowel. This includesresistant starch, β-glucan and other soluble and insoluble carbohydratepolymers. It is intended to comprise that portion of carbohydrates thatare fermentable, at least partially, in the large bowel by the residentmicroflora.

The starch of the invention preferably contains relatively high levelsof dietary fibre, more particularly amylose and optionally an elevatedlevel of β-glucan. The dietary fibre content of the grain of the presentinvention may or may not result solely from the increased relativeendospermal amylose content. The β-glucan may be present at elevatedlevels and as such may contribute significantly to the dietary fibrelevel.

Aspects of this invention might also arise from the combination ofaleurone layer and germ in combination with high levels of dietaryfibre. Specifically, this may arise where higher relative levels ofaleurone or germ are present in the grain. Firstly, barley has asignificantly higher aleurone layer than other commercial grains, beinga result of having a three cell aleurone layer. Secondly, where thebarley grain is slightly shrunken the endosperm is present in reducedamounts and the aleurone layer and the germ are present in relativelyelevated amounts. Thus the barley has a relatively high level of certainbeneficial elements or vitamins in combination with elevated resistant,such elements include divalent cations such as bioavailable Ca⁺⁺ andvitamins such as folate or antioxidant such as tocopherols andtocotrienols. Calcium is required for growth and deposition of bone andother calcified tissue and in lowering the risk of osteoporosis later inlife. Folic acid is found to be protective against neural tube defectswhen consumed periconceptually and decreases the risk of cardiovasculardisease, thereby enhancing the effects of the combination of resistantstarch and β-glucan. Folic acid also is thought to have an effect oflowering the risk of certain cancers. Tocopherol and tocotrienols carrythe benefits of antioxidants and are believed to lower the risk ofcancer and heart disease, and also have the effect of reducing theundesirable effects of oxidation of components of a food such as fattyacids which can result in rancidity. One specific form of milled productmight be one where the aleurone layer is included in the milled product.Particular milling process might be undertaken to enhance the amount ofaleurone layer in the milled product. Such a method is referred to inFenech et al. (1999). Thus any product derived from grain milled orotherwise processed to include aleurone layer and germ will have theadditional nutritional benefits, without the requirement of adding theseelements from separate sources.

Resistant Starch

Resistant starch is defined as the sum of starch and products of starchdigestion not absorbed in the small intestine of healthy humans butentering into the large bowel. Thus, resistant starch excludes productsdigested and absorbed in the small intestine. Resistant starches includephysically inaccessible starch (RS1 form), resistant granules (RS2),retrograded starches (RS3), and chemically modified starches (RS4).

The altered starch structure and in particular the high amylose levelsof the starch of the invention give rise to an increase in resistantstarch when consumed in food. Resistant starch may also increase ifβ-glucan is present at elevated levels, which is likely to exertprotective effects by association of the β glucan with the starchgranule. The starch may be in an RS1 form, being somewhat inaccessibleto digestion. Starch-lipid association as measured by V-complexcrystallinity is also likely to contribute to the level of resistantstarch. In this case the resistance is likely to arise because of thephysically inaccessible of the starch by virtue of the presence of thelipid and accordingly this might be regarded as an RS1 starch. Thestarch of the exemplified barley plant may be resistant to digestion byreason of the structure of the starch granule and accordingly may haveRS2 starch. Each of these characteristics might be present separately orin combination.

It will be understood that one benefit of the present invention is thatit provides for products that are of particular nutritional benefit, andmoreover it does so without the need to modify the starch or otherconstituents of the barley grain. However it may be desired to makemodifications to the starch, β-glucan or other constituent of the grain,and the invention encompasses such a modified constituent. Methods ofmodification are well known and include the extraction of the starch orβ-glucan or other constituent by conventional methods and modificationof the starches to increase the resistant form. The starch or β-glucanmay be modified by treatment with heat and/or moisture, physically (forexample ball milling), enzymatically (using for example α- or β-amylase,pullulanase or the like), chemical hydrolysis (wet or dry using liquidor gaseous reagents), oxidation, cross bonding with difunctionalreagents (for example sodium trimetaphosphate, phosphorous oxychloride),or carboxymethylation.

Glycemic Index

Glycemic Index (GI) is a comparison of the effect of a test food withthe effect of white bread or glucose on excursions in blood glucoseconcentration. The Glycemic Index is a measure of the likely effect ofthe food concerned on post prandial serum glucose concentration anddemand for insulin for blood glucose homeostasis. One important productprovided by the invention as a result of the high amylose and optionallyhigh β-glucan content is a low calorific product with a reduced glycemicindex. A low calorific product might be based on inclusion of flourproduced from milled barley grain. It might be desired, however, tofirst pearl the grain removing perhaps 10% or 20% by weight of thegrain, thereby removing the aleurone layer and at the greater reductionremoving also the germ. The effect of the pearling step is to reduce thelipid content and therefore reducing the calorific value of the food.Such foods will have the effect of being filling, enhancing bowelhealth, reducing the post-prandial serum glucose and lipid concentrationas well as providing for a low calorific food product. Use of thepearled product would result in a reduction in nutritional benefitsprovided by the aleurone layer and the germ. The flour produced from thepearled product is likely to have an enhanced appearance because aproduct made in that way tends to be whiter.

Non-Food Applications

The present invention provides modified or improved starches havingelevated levels of amylose or reduced levels of amylopectin whoseproperties satisfy any of various industrial requirements. Starch iswidely used in non-food industries, including the paper, textile,corrugating and adhesive industries (Young, 1984). The physicalproperties of unmodified starch limits its usefulness in someapplications and often imposes a requirement for chemical modificationthat can be expensive or have other disadvantages.

The invention provides starch for which less post-harvest modificationmay be required, in particular due to the reduced amylopectin content incombination with other physical properties. For example, the pastingtemperature, resistance to shearing stresses, film strength and/or waterresistance of starches and product made from the grain of this inventionmay be altered. The starch may also be used to prepare a biodegradableloose-fill packing material that can be used as a replacement forpolystyrene.

It will be understood that whilst various indications have been given asto aspects of the present invention, the invention may reside incombinations of two or more aspects of the present invention.

EXAMPLES Example 1 Materials and Methods

Callus Inducing Medium

BCI-DM medium containing Dicamba (2.5 mg/l) was used for callusinduction from barley embryo. Composition for one litre of medium:

MS salt Macro (10x stock): 100 ml MS micro (100x stock): 10 ml Iron(200x stock): 5 ml EDTA (200x stock): 5 ml Maltose: 15.0 g Thiamine-HCl(1 mg/ml): 1 ml Myo-inositol: 250 mg Casein hydrolysate: 1 g Dicamba (1mg/ml): 2.5 ml Proline: 345 mg

The pH was adjusted to 5.8 and 3.5 g/l of Phytagel added. Afterautoclaving the medium, 150 mg/l of Timentin and 50 mg/l of Hygromycinwere added.

Barley Regeneration Medium

Barley calli are regenerated in FHG medium containing BAP (1 mg/l)

FHG-I Macro (10x stock): 100 ml FHG-II Micro (100x stock): 10 mlThiamine-HCl (1 mg/ml): 1 ml Iron (200x stock): 5 ml EDTA (200x stock):5 ml BAP (1 mg/ml): 1 ml Inositol: 100 mg Glutamine: 730 mg Maltose: 62g

The pH was adjusted to 5.8 and then 3.5 g/l of phytagel added. Afterautoclaving the medium, 150 mg/l of Timentin and 20 mg/l of hygromycinwere added.

Carbohydrate Determination and Analysis

Starch was isolated from barley grain using the method of Schulman etal. (1991). Starch content was determined using the total starchanalysis kit supplied by Megazyme (Bray, Co Wicklow, Republic ofIreland). The starch content is then compared to control plants.Subtraction of the starch weight from the total grain weight to give atotal non-starch content of the grain determines whether the reductionin total weight is due to a reduction in starch content.

Determination of the amylose content or the amylose/amylopectin ratiowas performed by an HPLC method for separating debranched starches or byan iodine binding method, as described by Batey and Curtin (1996).Briefly, starch was defatted by dissolving it in DMSO andreprecipitation with ethanol. After redissolving the starch in DMSO andthe addition of water, further dilution, and addition of aniodine/potassium iodide solution, the absorbance of the solution wasmeasured at 605 nm. The amylose content was determined from a standardcurve obtained from mixtures of amylose and amylopectin covering therange 0-100% amylose. Analysis of the amylose/amylopectin ratio ofnon-debranched starches may also be carried out according to Case etal., (1998).

β-Glucan levels were determined using the kit supplied by Megazyme(Bray, Co Wicklow, Republic of Ireland).

Starches were debranched and chain length distributions analyzed usingfluorophore assisted carbohydrate electrophoresis (FACE) using acapillary electrophoresis unit according to Morell et al (1998).

Differential Scanning Calorimetry (DSC)

DSC measures the changes to gelatinisation temperatures that haveoccurred in the starch by changes in amylose and amylopectin ratio.Gelatinisation was measured in a Pyris 1 differential scanningcalorimeter (Perkin Elmer, Norwalk Conn., USA). Starch was mixed withwater in the ratio of 2 parts water:1 part starch and this mixture(40-50 mg, accurately weighed) placed in a stainless steel pan andsealed. The sample was scanned at 10° C. per minute from 20° C. to 140°C. with an empty stainless steel pan as a reference. Gelatinisationtemperatures and enthalpy were determined using the Pyris software.

RVA Analysis

Viscosity was measured on a Rapid-Visco-Analyser (RVA, NewportScientific Pty Ltd, Warriewood, Sydney) using conditions as a reportedby Batey et al., 1997 for wholemeal flours. In order to inhibitα-amylases, silver nitrate was included in all assays at a concentrationof 12 mM. The parameters measured were peak viscosity (the maximum hotpaste viscosity), holding strength, final viscosity and pastingtemperature.

Flour Swelling

Flour swelling volume was determined according to the method ofKonik-Rose et al (2001). Increased uptake of water was measured byweighing the sample prior to and after mixing the sample in water atdefined temperatures and following collection of the gelatinizedmaterial.

Example 2 Isolation of SBE Genes from Barley

Construction of Barley cDNA and Genomic Libraries

Barley cDNA and genomic libraries were made by standard methods in phagevectors (Sambrook et al, 1989). A cDNA library was made in the ZipLoxvector (Life Technology) according to the protocols supplied with thereagents. The titre of the library was 2×10⁶ pfu tested with Y1090 (ZL)strain of E. coli. The barley genomic library, obtained from E. Lagudah(CSIRO), was made from DNA from the variety Morex. The DNA was digestedwith MboI and ligated to EcoRI/BamHI digested EMBL3 cos vector. Clonedfragments could be released with SalI digestion.

Isolation of SBEIIa and SBEIIb Gene Sequences from a H. vulgare GenomicLibrary

Conditions for library screening were hybridisation at 25% formamide,5×SSC, 0.1% SDS, 10×Denhardts solution, 100 μg/ml salmon sperm DNA at42° C. for 16 hr, followed by washing with 2×SSC, 0.1% SDS at 65° C. for3×1 hr (medium stringency). Clones containing the SBEIIa and SBEIIbgenes or substantial portions thereof were isolated and sequenced. DNAsequence comparisons to those of the Accession Nos. listed in Table 1confirmed that both genes of interest had been isolated from barley.SBEIIa and SBEIIb cDNA sequences may also be obtained using reversetranscription-PCR (RT-PCR) with specific primers, a technique well knownin the art. Barley SBEIIa and SBEIIb cDNA sequences are shown in FIGS. 1and 2, and wheat SBEIIa and SBEIIb genomic sequences shown in FIGS. 3and 4.

TABLE 1 Starch branching enzyme genes characterized from cereals SBESpecies isoform Type of clone Accession No. Reference Maize SBE I cDNAU17897 Fisher et al., 1995 genomic AF072724 Kim et al., 1998a SBE IIbcDNA L08065 Fisher et al., 1993 genomic AF072725 Kim et al., 1998 SBEIIa cDNA U65948 Gao et al., 1997 Wheat SBE II cDNA Y11282 Nair et al.,1997 SBE I cDNA and AJ237897 SBE I gene) Baga et al., 1999 genomicAF002821 (SBE I Rahman et al., 1997, pseudogene Rahman et al., 1999AF076680 (SBE I gene) AF076679 (SBE I cDNA) SBE I cDNA Y12320 Repellinet al., 1997 SBE IIa cDNA and AF338432 (cDNA) Rahman et al., 2001genomic AF338431 (gene) Rice SBE I cDNA D10752 Nakamura and Yamanouchi,1992 SBE I genomic D10838 Kawasaki et al., 1993 SBE3 cDNA D16201 Mizunoet al., 1993 Barley SBE IIa and cDNA and AF064563 (SBE IIb Sun et al.,1998 SBE IIb genomic gene) AF064561 (SBE IIb cDNA) AF064562 (SBE IIagene) AF064560 (SBE IIa cDNA)

Example 3 Constructs for Transformation Experiments to Alter BarleySBEIIA and SBEIIB Expression

Duplex-RNA (dsRNA) constructs were made to reduce the expression ofeither the SBEIIa or SBEIIb genes of barley. In such constructs, thedesired nucleic acid sequence corresponding to part of the SBEIIa orSBEIIb genes occurred in both the sense and antisense orientationsrelative to the promoter so that the expressed RNA comprisedcomplementary regions that were able to basepair and form a duplex ordouble-stranded RNA. A spacer region between the sense and antisensesequences comprised an intron sequence which, when transcribed as partof the RNA in the transformed plant, would be spliced out to form atight “hairpin” duplex structure. The inclusion of an intron has beenfound to increase the efficiency of gene silencing conferred byduplex-RNA constructs (Smith et al, 2000). The desired nucleic acid waslinked to a high molecular weight glutenin (HMWG) promoter sequence(promoter of the DX5 subunit gene, Accession No. X12928, Anderson etal., 1989) and terminator sequence from the nopaline synthase gene fromAgrobacterium (nos3′).

Duplex-RNA constructs containing SBEIIa or SBEIIb sense/antisensefragments, obtained from wheat SBEIIa and SBEIIb genes in view of thehigh degree of sequence identity between the wheat and barley genes,were initially generated in the vector pDV03000 and then cut out andligated to the barley transformation vector pWBVec8. The constructs areshown schematically in FIG. 5. The vector pWBVec8 contains a number ofrestriction enzyme sites for incorporation of desired DNA sequences.

The SBEIIa duplex-RNA construct contained 1536 bp of nucleotide sequenceamplified by PCR from the wheat SBEIIa gene (GenBank Accession numberAF338431, see FIG. 3). This included; a 468 bp sequence that comprisesthe whole of exons 1 and 2 and part of exon 3 (nucleotide positions 1058to 1336, 1664 to 1761 and 2038 to 2219 in FIG. 3), with EcoRI and KpnIrestriction sites on either side (fragment 1), a 512 bp sequenceconsisting of part of exons 3 and 4 and the whole of intron 3 of SBEIIa(nucleotide positions 2220 to 2731 in FIG. 3) with KpnI and SacI siteson either side (fragment 2) and a 528 bp fragment consisting of thecomplete exons 1, 2 and 3 of SBEIIa (nucleotide positions 1058 to 1336,1664 to 1761 and 2038 to 2279 in FIG. 3) with BamHI and SacI sites oneither side (fragment 3). Fragments 1, 2 and 3 were then ligated so thatthe sequence of fragment 3 was ligated to fragment 2 in the antisenseorientation relative to fragment 1. The gene construct in the vectorpDV03000 was designated pDV03-IIa and the duplex-RNA gene designatedds-SBEIIa.

The strategy for the SBEIIb duplex-RNA construct was similar. The SBEIIbconstruct contained a fragment of 1607 bp amplified by PCR from thewheat SBEIIb gene (sequence is outlined in FIG. 4). This included; a 471bp sequence that comprises the whole of exons 1 and 2 and part of exon 3(nucleotide positions 489 to 640, 789 to 934 and 1598 to 1769 in FIG.4), with EcoRI and KpnI restriction sites on either side (fragment 1), a589 bp sequence consisting of part of exons 3 and 4 and the whole ofintron 3 of SBEIIb (nucleotide positions 1770 to 2364 in FIG. 4) withKpnI and SacI sites on either side (fragment 2) and a 528 bp fragmentconsisting of the complete exons 1, 2 and 3 of SBEIIb (nucleotidepositions 489 to 640, 789 to 934 and 1598 to 1827 in FIG. 4) with BamHIand SacI sites on either side (fragment 3). Fragments 1, 2 and 3 werethen ligated so that the sequence of fragment 3 was ligated to fragment2 in the antisense orientation relative to fragment 1. The SBEIIbduplex-RNA gene construct in the vector pDV03000 was designatedpDV03-IIb and the duplex-RNA gene designated ds-SBEIIb.

The promoter-sense/antisense-terminator cassettes were inserted into thebinary vector pWBVec8 using the restriction enzymes ApaI and NotI. TheSBEIIa construct in pWBVec8 was designated pVec8-IIa and the SBEIIbconstruct in pWBVec8 was designated pVec8-IIb. The constructs are shownschematically in FIG. 5.

The identity between the wheat SBEIIa sequences used and thecorresponding barley SBEIIa sequence was 93% using the program Gap tocompare the sequences. Similarly, the identity between the wheat SBEIIbsequence and the corresponding barley SBEIIb sequence was 92%.Duplex-RNA technology is effective for silencing the expression of geneshaving sequences with identities over about 85% with respect to theduplex region, and so the expectation was that the duplex constructedwith the wheat sequences would be effective against the barleysequences.

Example 4 Transformation of Barley

Methods for the transformation of barley, mediated by Agrobacteriumtumefaciens or by biolistics, have been described (Tingay et al., 1997;Wan et al, 1994) and can be used to transfer DNA constructs generatingtransgenic plants. In this example, the gene constructs in binaryvectors, made as described above, were introduced into a highly virulentAgrobacterium strain by tri-parental conjugation, which was then used tointroduce the T-DNA containing the inhibitory gene (ds-SBEIIa ords-SBEIIb) and the selectable marker gene (encoding hygromycinresistance, expressed from the CaMV35S promoter) into regenerable cellsof the scutellum of immature barley embryos, as follows.

Developing barley seeds from the variety Golden Promise, 12-15 daysafter antithesis, were removed from the growing spike of greenhousegrown plants, and sterilised for ten minutes in 20% (v/v) bleachfollowed by rinsing once with 95% ethanol and seven times with sterilewater. Embryos (approx 1.5 to 2.5 mm in size) were then removed from theseeds under aseptic conditions and the axis cut from each embryo. Theembryos were placed cut side down on a petri dish containing callusinduction medium. The Agrobacterium transconjugants (strain AGL1) weregrown in MG/L broth (containing 5 g mannitol, 1 g L-glutamic acid, 0.2 gKH₂PO₄, 0.1 g NaCl, 0.1 g MgSO₄.7H₂O, 5 g tryptone, 2.5 g yeast extractand 1 μg biotin per litre, pH 7.0) containing spectinomycin (50 mg/l)and rifampicin (20 mg/l) with aeration at 28° C., to a concentration ofapproximately 2-3×10⁸ cells/ml, and then approx 300 μl of the cellsuspension was added to the embryos in a petri dish. After 2 min, excessliquid was tipped from the plate and the embryos were flipped so thatthe cut side (axil side of the scutellum) was upwards. The embryos werethen transferred to a fresh plate of callus inducing medium and placedin the dark for 2-3 days at 24° C. The embryos were transferred tocallus inducing medium with selection (50 μg/ml hygromycin and 150 μg/mltimentin). Embryos remain on this media for 2 weeks in the dark at 24°C. Healthy callus was then divided and placed on fresh selection mediaand incubated for a further two weeks at 24° C. in the dark. Followingthis, the embryos were incubated at 24° C. in the light for 2 weeks onregeneration medium containing cytokinin and transferred to rootingmedia containing cytokinin and auxin for three 2 week periods. Juvenileplants were then transferred to soil mixture and kept on a misting benchfor two weeks and finally transferred to a glasshouse. A total of 400embryos using pVec8-IIb and 300 embryos using pVec8-IIa were treated bythis method and 18 plants from 7 calli for the IIb transformation and 18plants from 14 calli for the IIa transformation survived on selectionmedium, suggesting that they were successfully transformed with the geneconstruct. Not all of the plants that were transformed with theselectable marker gene would be expected to integrate the SBEIIa orSBEIIb inhibitory gene; these could readily be distinguished asdescribed in the following examples.

Example 5 Analysis of Barley Plants and Grain Transformed withDuplex-RNA Constructs

The presence or absence of the transgene(s) in barley plants or progenyseed or plants was determined or confirmed by PCR techniques or Southernblot hybridisation analysis. DNA was prepared from leaf samples fromputative transformed plants by standard methods.

PCR Analysis of Transformed Barley Plants—Detection of Transgenes.

The forward and reverse primers used for screening the presence of theds-SBEIIa transgene were BX17 3′ (5′-CAA CCA TGT CCT GAA CCT TCA CC-3′)SEQ ID No. 5 and AR2akpnR (5′-GGT ACC CCA TCT CCT GGT TTT GGG ACA AC-3′)SEQ ID No. 6, respectively. This primer pair amplified a 569 bp product,corresponding to a position within the HMWG promoter sequence of thetransgene to the nucleotide position 2219 in FIG. 3, from those plantscontaining the ds-SBEIIa transgene. The primers used for screening forthe presence of the ds-SBEIIb transgene were BX17 3′ (as above) andAR2bkpnR (5′-GGT ACC GTC CAT TTC CCG GTG GTG GCA G-3′) SEQ ID No. 7.This primer pair amplified a 571 bp product, corresponding to a positionwithin the HMWG promoter to nucleotide position 1768 in FIG. 4, fromthose lines containing the ds-SBEIIb transgene. PCR amplification wasconducted in a 20 μl reaction containing 2.5 units Hotstar Taq, 1×buffer supplied with the enzyme containing 1.5 mM MgCl₂, 0.125 mM eachdeoxynucleotide triphosphate (dNTPs), 1 μM each of the forward andreverse primers and 100 ng DNA. The PCR programme included an initialdenaturation step of 95° C. for 5 min, followed by 36 cycles of 95° C.for 30 sec, 59° C. for 1 min and 72° C. for 2 min, finished with 72° C.for 5 min.

Positive barley transformants were identified for both of the SBEIIa andSBEIIb constructs (FIG. 6). The data is summarized in Table 2.

TABLE 2 Summary of PCR and Southern hybridization results of SBEIIa andSBEIIb transgenic lines of barley. SBEIIb SBEIIa transgenic Transform.transgenic Transform. line No. event no.^(a) PCR Southern line No. eventno.^(a) PCR Southern IIb1.1 1 − − IIa1.1 1 − − IIb1.2 1 − − IIa2.1 2 − −IIb1.3 1 +    + (vf) IIa3.1 3 + − IIb2.1 2 + + IIa3.2 3 + − IIb2.2 2 + +IIa4.1 4.1 + + IIb3.1 3 + + IIa4.2 4.2 + + IIb4.1 4 + + IIa5.1 5 + nrIIb4.2 4 + + IIa5.2 5 + + IIb4.3 4 + + IIa6.1 6 + + IIb4.4 4 + + IIa6.26 + + IIb4.5 4 + + IIa7.1 7 − − IIb4.6 4 − + IIa9.1 9 + nr IIb5.1 5 +  + (f) IIa10.1 10 + nr IIb8.1 8 + − IIa11.1 11 − − IIb8.3 8 + − IIa13.213 + nr IIb8.4 8 +   + (f) IIa13.3 13 + nr IIb9.1 9 + + IIa15.1 15 + nrIIa16.1 16 − − ^(a)Transformation event Nos. with the same number wereisolated from the same callus and may be identical or independent.Different numbers: independent transformants. (f): faint; (vf): veryfaint; nr: no resultSouthern Blot Hybridization Analysis of Transformed Barley.

Southern blot hybridization analysis was carried out on DNA from theds-SBEIIa and ds-SBEIIb transgenic plants and their progeny to confirmthe PCR results. EcoRI digested DNA, prepared from the plants bystandard methods, was electrophoresed on 1% agarose gels and blotted onto Hybond N+ nylon membrane (Amersham). Radio-labelled probes weregenerated from the intron 3 region of the SBEIIa (positions 2220 to 2731see FIG. 3) and SBEIIb (positions 2019 to 2391 see FIG. 4) genes. Thesesegments are part of the respective ds-SBEIIa and ds-SBEIIb constructs(Example 3) and were radioactively labeled using the Megaprime DNAlabeling system (Amersham Pharmacia Biotech UK Ltd) and used forhybridization. The hybridization was carried out in 25% (v/v) formamide,5×SSC, 0.1% SDS, 10×Denhardt's solution, 100 μg/ml salmon sperm DNA at42° C. for 16 hr followed by washing in 2×SSC, 0.1% SDS at 65° C. for3×1 hr. Autoradiography of the membranes revealed positive hybridizingbands in lanes corresponding to plants that were positive for theconstructs (FIG. 7). The endogenous barley SBEIIa and SBEIIb genefragments were not detected in the hybridization because of sequencedivergence with the wheat intron 3 probe used.

The results of the PCR and Southern hybridization analyses aresummarized in Table 2. In general, the PCR and Southern hybridizationresults correlated well. Discrepancies may have been due to falsenegatives and would readily be resolved by repeated assays. Plants thatwere positive for the transgenes as demonstrated by both methodsincluded 4 independent transformation events for ds-SBEIIa Southern (IIa4.1, IIa 4.2, IIa 5 and IIa 6) and 5 independent events for ds-SBEIIb(Event no. IIb 2, IIb3, IIb4, IIb5 and IIb 9).

Analysis of Barley Endosperm Proteins by Polyacrylamide GelElectrophoresis (PAGE).

To determine the effect of the ds-SBEIIa and ds-SBEIIb transgenes on thebarley SBEIIa and SBEIIb gene expression in the transformed plants,specific protein expression in endosperm tissue of developing grains wasdetected by non-denaturing PAGE and Western blot analysis. Since the T1seeds (seeds from T0 plants) were expected to be segregating for thetransgenes, endosperm from each of ten individual developing T1 grainsfrom each T0 plant, at 20 days after flowering, were analyzed for SBEIIaand SBEIIb protein expression. To preserve the T1 plants, embryos wererescued from the developing grains and cultured to regenerate the T1plants. Endosperm dissected away from all maternal tissues (0.2 g) washomogenized in 600 μl of 50 mM KPi buffer (42 mM K₂HPO₄ and 8 mMKH₂PO₄), pH 7.5 containing 5 mM EDTA, 20% glycerol, 5 mM DTT and 1 mMPefabloc. The ground samples were centrifuged for 10 min at 13,000 g andthe supernatant aliquoted and frozen at −80° C. until use. Proteinlevels were measured with Coomassie reagent with BSA as a standard.Total soluble proteins, equivalent to 20 μg, extracted from eachendosperm, were loaded per lane and electrophoresed in 8% non-denaturingpolyacrylamide gels containing 0.34 M Tris-HCl (pH 8.8), acrylamide(8.0%), ammonium persulphate (0.06%) and TEMED (0.1%). Followingelectrophoresis, the proteins were transferred to a nitrocellulosemembrane according to Morell et al., (1997) and immunoreacted withSBEIIa or SBEIIb specific antibodies. The antibody used for detection ofSBEIIa was 3KLH, from rabbits, which had been raised against thesynthetic peptide AASPGKVLVPDESDDLGC SEQ ID No. 8 (the sequence from theN-terminus of SBEIIa), and was diluted 1:5000 for use. The antibody usedfor detection of SBEIIb was R6, raised against the synthetic peptideAGGPSGEVMIGC SEQ ID No. 9 (the deduced sequence from the N-terminus ofSBEIIb) and diluted 1:6000 before use. The secondary antibody used wasGAR-HRP conjugate (1:3000 dilution), and immunoreactive bands wererevealed using an Amersham ECL-detection system.

The protein expression in the developing T1 seeds from plantstransformed with the ds-SBEIIa or ds-SBEIIb genes appeared to besegregating in a 1:2:1 ratio of strong bands:moderate-weak bands:nobands for some of the transformed lines (for example, see FIGS. 8 and9). This ratio corresponds to the expected segregation ratio ofhomozygotes (wild type=null for transgene): heterozygotes: homozygousfor the transgene. The T1 plants from the rescued embryos are grown toproduce T2 seed which are screened by PCR and protein expressionanalysis to confirm the genetic status of the T1 seed with respect tothe transgene.

These data indicate that the duplex-RNA constructs are effective inreducing the expression of the SBEIIa and SBEIIb genes in endosperm ofbarley.

The expression of the SBEIIb gene in transgenic seeds containing theds-SBEIIa transgene, and the expression of the SBEIIa gene in seedscontaining the ds-SBEIIb were also analyzed by the Western blot method.Unexpectedly, transgenic seeds comprising ds-SBEIIa, for example fromthe transformation event IIa 4.1, were much reduced for SBEIIb. See FIG.9 which shows only a low level of expression of SBEIIb in seeds fromline IIa 4.1.8 (note the very weak bands in 4 of the 7 lanes). This linecontained the ds-SBEIIa transgene and had negligible SBEIIa expression.However, the converse effect was not observed in seeds transgenic fords-SBEIIb. The SBEIIa expression was unaltered in the seeds in whichSBEIIb was completely silenced by ds-SBEIIb (FIG. 10) namely, fortransgenic lines from the transformation events IIb 4 and IIb 2. Theregion including exons 1-3 was used for both ds-SBEIIa and ds-SBEIIbduplex constructs. Alignment of the sequences of SBEIIa and SBEIIb inthis region revealed only ˜70% identity. The longest stretch of 100%identity was a region of 21 bp in the exon 2. Although it is stillpossible that expression of SBEIIb was suppressed by the ds-SBEIIaconstruct due to sequence homology, it is also possible that theactivity of SBEIIb was reduced by the ds-SBEIIa transgene by some othermechanism.

The expression levels of the SBEIIa and SBEIIb genes can also bespecifically determined at the mRNA levels through standard techniquessuch as Northern hybridisation or RT-PCR methods, for example by usingprobes from non conserved regions or primer pairs which hybridize tounique sites in one of the genes but not the other, for example in the3′ untranslated regions. Such regions or sites can readily be identifiedby comparison of the two gene sequences.

Example 6 Analysis of Grain Composition and Content, Including Starch

The grain composition and content, particularly for starch, may bemeasured using standard techniques such as those described in Example 1.

After extraction of the soluble proteins as described above, the starchgranules from individual endosperm samples from developing seedscontaining the ds-SBEIIa transgene were visualized under a lightmicroscope. A significant alteration in starch granule morphology wasobserved (see for Example FIG. 11) in developing endosperm that werereduced in SBEIIa expression for three of the five transformation eventsexamined: IIa 4.1, IIa 4.2 and IIa 13, but not for events IIa 5 or IIa 6which may have had a lesser degree of gene inactivation. For example,starch from IIa 4.2.5 seeds, which had no SBEIIa band in the proteinimmunoblot, was highly distorted compared to the normal granules in IIa4.2.3 seeds, which had a strong SBEIIa band in the protein immunoblot(Table 3). Light microscopy results were confirmed by scanning electronmicroscopy (SEM), which may also be used to view starch granulesdirectly. To do this, purified starch was sputtered with gold andscanned at 15 kV at room temperature. Seeds reduced for SBEIIaexpression showed a distorted irregular shape that was visible under thescanning electron microscope, for example the distortion of granules inIIa 4.2.5 seeds compared to IIa 4.2.3 seeds (FIG. 12).

In contrast to the plants containing ds-SBEIIa, the plants transformedwith ds-SBEIIb showed endosperm starch granules with normal morphologywhen examined by microscopy, for example line IIb 4.1 (see Table 3).This suggests that reduction of SBEIIb expression alone did notsubstantially alter starch granule morphology.

TABLE 3 Starch granule morphology of T1 endosperm tissues of barleyds-SBEIIa and ds-SBEIIb transgenic lines Starch granule Protein band onmorphology No Transgenic line immunoblot (light microscopy) 1 IIa 4.1.8No band Distorted 2 IIa 4.1.4 Strong band normal 3 IIa 4.1.3 Strong bandnormal 4 IIa 4.2.1 No band Distorted 5 IIa 4.2.9 No band distorted 6 IIa4.2.5 No band distorted 7 IIa 6.2.8 No band normal 8 IIa 5.2.3 No bandnormal 9 IIa 6.2.2 Strong band normal 10 IIa 4.2.3 Strong band normal 11IIa 13.1.9 No band normal 12 IIa 13.1.10 Weak band normal 13 IIa 13.1.3Strong band normal 14 IIa 13.2.4 No band Some distortion 15 IIa 13.1.6Weak band normal 16 IIb 4.1.9 No band normal 17 IIb 4.1.8 No band normal18 IIb 4.1.2 No band normal

Birefringence is the ability of a substance to refract light in twodirections; this produces a dark cross called a “maltese cross” on eachstarch granule when viewed with a polarizing microscope. Birefringenceis an indicator of the degree of ordered structural organization of thepolymers within the granules (Thomas and Atwell, 1999). Starch granulesfrom endosperm of IIa 4.2.5 seeds (reduced for SBEIIa activity) underpolarized light indicated that there is a significant loss ofbirefringence in these granules compared to that from IIa 4.2.3 seeds(wild type) On average, 44.8% of the granules in IIa 4.2.5 seeds werewithout birefringence in contrast to 2.2% in IIa 4.2.3 seeds (Table 4).Loss of birefringence in starch granules is generally well correlatedwith increased amylose content.

TABLE 4 Birefringence of starch granules from T1 endosperm of ds-SBEIIabarley transgenic lines No. of No. of No. of Micro- granules granulesgranules scopic showing showing showing Line field no BF partial BF fullBF A4.2.5 1 38 19 12 (SBEIIa 2 48 22 9 negative) 2 26 25 35 4 17 12 25Total 129 (44.8%) 78 (27.1%) 81 28.1%) A4.2.3 1 5 8 205 (control) 2 3 9104 3 3 5 200 4 2 2 85 Total 13 (2.1%) 24 (3.8%) 593 (94.1%) BF:Birefringence

Grain weight analysis of transgenic seeds, from plants grown in thegreenhouse, from the line IIa 4.2 containing ds-SBEIIa, revealed thatthere was no significant reduction in grain weight and therefore starchproduction, even in the seeds with highly distorted starch granules(Table 5). This is in contrast to the reduced grain weight observed inbarley that is mutant in the SSIIa gene, which shows significantlyreduced starch production (Morell et al, 2003). This suggests that theaverage grain weight and therefore the yield of field-grown barley withreduced SBEIIa activity in the endosperm is about normal.

TABLE 5 Grain weight of T1 seeds from the SBE IIa barley transgenic lineIIa 4.2 Seed from line Starch granule Grain weight No. No.: morphology(mg) 1 IIa 4.2.1 Normal 46.4 2 IIa 4.2.2 Highly 39.3 distorted 3 IIa4.2.3 Distorted 39.0 4 IIa 4.2.4 Distorted 40.8 5 IIa 4.2.5 Highly 37.3distorted 6 IIa 4.2.6 Normal 41.8 7 IIa 4.2.7 Normal 35.0 8 IIa 4.2.8Highly 41.5 distorted 9 IIa 4.2.9 Highly 41.1 distorted 10 IIa 4.2.10Highly 38.6 distortedAmylose and Amylopectin Levels in Transgenic Barley Grain.

Seed with starch granules having a distorted shape have been reported inhigh amylose barley (Morell et al, 2003) and in low amylopectin (LAPS)maize having about 90% amylose in starch (Sidebottom et al., 1998).Amylose content may be determined by size exclusion HPLC in 90% (w/v)DMSO, or by iodine blue value (iodometric method), as described inExample 1. From the grain weight and amylose content, the amount ofamylose deposited per grain can be calculated and compared fortransgenic and control lines.

Starch was isolated from barley grains of the T1 generation, segregatingfor ds-SBEIIa, or the T2 generation (probably homozygous for ds-SBEIIa)from plants transgenic for the ds-SBEIIa gene, or resulting from a crossbetween line IIa 4.2.5 and line IIb 4.3.8 (containing both ds-SBEIIa andds-SBEIIb), and the amylose contents determined by the colorimetricmethod of Morrison and Laignelet (1983). The amylose content of starchfrom five pooled grain samples, listed below, was determined. Theabsorbance read at 650 nm was converted to percentage amylose contentusing the regression equation derived from standard samples (rangingfrom 0 to 100% amylose) made from potato amylose and amylopectin,Y=137.38x−30.361, where x is the absorbance at 650 nm and Y is thepercentage amylose content.

Samples:

Pool 1: seven T1 seeds that showed severe starch granule distortion fromthe transgenic line IIa 4.1

Pool 2: six T1 seeds that showed some granule distortion from thetransgenic line IIa 4.1

Pool 3: seven T1 seeds that had normal looking granules from thetransgenic line IIa 4.1

Pool 4: six T2 seeds that showed severe granule distortion from thetransgenic line IIa 4.2.5

Pool 5: five F1 seeds that showed severe starch granule distortion fromthe cross between IIa 4.2.5 and IIb 4.3.8 (ds-SBEIIb transgenic line).

Controls: Barley SSIIa mutant M292 (Morel et al., 2003), barley cvHimalaya and SSIIa wheat mutant (Yamamori et al. 2000).

Starch from grains from barley with reduced SBEIIa activity, based onthe distorted starch granules, showed more than 80% amylose. The amylosecontent increased with the degree of distortion of the starch granules,compare pools 1, 2 and 3 (Table 6). The amylose contents for pools 1 and2 were higher than for starch from the SSIIa mutant barley line M292(Table 6). The amylose content was even higher (>90%) in the pool 5consisting of F1 grains from the cross between the ds-SBEIIa andds-SBEIIb transgenic lines. It is noted that the absorbance valuesobtained by this method may be influenced slightly by the structure ofamylopectin.

TABLE 6 Amylose content in the grain of transgenic barley lines reducedfor SBEIIa activity. Amylose content (% of starch) Starch sampleReplication 1 Replication 2 Replication 3 Mean Pool 1 85.0 80.2 80.281.8 Pool 2 60.6 52.1 51.7 54.8 Pool 3 39.4 40.5 40.0 40.0 Pool 4 84.484.6 88.3 85.8 Pool 5 95.3 94.8 106.1 98.7 M292 barley 66.9 60.5 58.461.9 Himalaya barley 21.8 21.6 22.3 21.9 SSIIa wheat mutant 52.1 46.754.5 51.1

This implies that the amylopectin content in the starch of these grainsis considerably reduced, from about 75% in wild-type to less than 20% oreven less than 10%, since cereal starch is made up almost entirely ofamylose and amylopectin.

Example 7 Mutation of SBEIIA Gene in Barley

Mutation of the SBEIIa gene in barley leading to non expression ofSBEIIa can be achieved through either gamma ray irradiation or chemicalmutagenesis, for example with ethyl methane sulfonate (EMS). For gammaray induced mutation, seeds are irradiated at a dose of 20-50 kR from a⁶⁰Co source (Zikiryaeva and Kasimov, 1972). EMS mutagenesis is performedby treating the seeds with EMS (0.03%, v/v) as per Mullins et al.,(1999). Mutant grains are identified on the basis of increased amylosecontent or altered starch grain morphology and confirmed by the methodsdescribed above. Mutants in SBEIIa can be re-mutagenized in a secondround and the progeny screened for loss of SBEIIb activity in additionto SBEIIa, or the SBEIIa mutant can be crossed with an SBEIIb mutant tocombine the mutations and produce a non-transgenic variety of barleysubstantially lacking SBEII activity in the endosperm.

Example 8 Cloning of the SBEI Gene and Constructs for Inhibition of SBEIExpression in Barley

Isolation of the SBEI gene is achieved by hybridization of probes to thebarley cDNA or genomic library or by PCR methods. The PCR primer designmay be based on the homologous genes from wheat, for example, based onthe DNA sequence set forth in Genbank AF076679. The primers used mightbe 5′ ACGAAGATGCTCTGCCTCAC 3′ SEQ ID No. 10 and 5′ GTCCAACATCATAGCCATTT3′ SEQ ID No 11 which should result in a PCR product of about 1015 bp.

The SBEI gene sequences are used to construct inhibitory gene constructsin a similar fashion to those described above for SBEIIa and SBEIIb, andintroduced into barley.

Example 9 Combination of SBEIIA Mutants with Other Starch SynthesisMutants

Plants transgenic for ds-SBEIIa and reduced for SBEIIa activity werecrossed with the barley lines M292 (SSIIa mutant) and High AmyloseGlacier (HAG). The following crosses were established:

-   -   1) line IIa 4.1.10×HAG    -   2) line IIa 4.1.16×HAG    -   3) line IIa 4.1.20×M292    -   4) line IIa 4.1.19×HAG

The F1 plants are self-fertilized and lines homozygous for bothmutations are identified by genetic and molecular analysis. Combiningthe ds-SBEIIa transgene with the SSIIa mutation is expected to yieldstarches with very high amylose content together with high β-glucancontent. Combining the ds-SBEIIa transgene with the HAG mutation mayyield further alteration in starch composition with improvedfunctionality in addition to high amylose content.

Example 10 Characteristics of Field-Grown Barley

Kernel weights and β-glucan contents were measured for severalfield-grown varieties of barley including the M292 and M342 lines (ssIIamutant, approx 60-65% amylose). It is noted from the results (Table 7)that M292 and M342 grain were reduced in kernel size and increased inβ-glucan content relative to the wild-type varieties (3.0-6.0%β-glucan). The average weight of field-grown wild-type grain was in therange 35-45 g/1000 kernels, grown under these conditions. The β-glucancontent in the grain of wild-type varieties was in the range 3-6%.

TABLE 7 Kernel weight and β-glucan levels in field-grown barley. 1000kernel weight ^(a) Cultivar (g) % beta-glucan ^(a) Tantangera 34.90,35.40 3.01, 3.37 Sloop 37.90, 41.90 3.04, 2.54 Waxiro 36.60, 37.10 5.14,6.86 Schooner 42.60, 38.60 3.85, 3.73 Gairdner 44.80, 37.10 4.61, 4.19Namoi 40.80, 40.80 5.19, 4.34 Himalaya 39.60, 37.90 6.04, 5.50 M29225.10, 28.70 10.01, 9.53  M342 28.90, 30.30 8.02, 8.65 Tantangera × M292DH 21.20, 20.40  9.08, 10.95 ^(a) Duplicate values are given, forseparate plots in the field.

It will be apparent to those skilled in the art that variousmodifications and alterations to these methods may be made withoutdeparting from the scope of the invention.

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1. A process for making a food product, comprising a) obtaining barleygrain comprising a genetic variation which reduces the activity ofSBEIIa by 40%, and a reduced level of SBEIIa and SBEIIb proteins in itsendosperm, relative to barley grain of the Golden Promise variety, andstarch comprising amylose, wherein the amylose content of the starch asmeasured by an iodometric method is at least 40% (w/w) of total starchcontent of the barley grain, b) optionally processing the barley grainto produce milled, ground, pearled, rolled, kibbled or cracked grain,flour, wholemeal or starch therefrom, and c) including the barley grainof a), or the milled, ground, pearled, rolled, kibbled or cracked grain,flour, wholemeal or starch of b) as an ingredient in the food product,to thereby make the food product.
 2. The process of claim 1, wherein thebarley grain has a starch content of at least 25% (w/w).
 3. The processof claim 2, wherein the barley grain has a starch content of at least35% (w/w).
 4. The process of claim 3, wherein the barley grain has astarch content of 45-50% (w/w).
 5. The process of claim 1, wherein thebarley grain has an average length to thickness ratio of less than 3.5.6. The process of claim 1, wherein the barley grain has an averageweight of at least 36 mg.
 7. The process of claim 1, wherein the amylosecontent of the starch is at least 50% (w/w).
 8. The process of claim 1,wherein the amylose content of the starch is at least 60% (w/w).
 9. Theprocess of claim 1, wherein the barley grain does not exhibit purplecoloration.
 10. The process of claim 1, wherein the barley graincomprises 3-6% (w/w) β-glucan as a percentage of total non-hulled grainweight.
 11. The process of claim 1 wherein the barley grain isnon-shrunken.
 12. The process of claim 1, wherein the starch has anincreased gelatinization temperature relative to starch from barleygrain of the Golden Promise variety, as measured by differentialscanning calorimetry.
 13. The process of claim 1, wherein the foodproduct is bread, cake, biscuits, noodles, quick soup or breakfastcereal.
 14. A process for making a food product, comprising a) obtainingbarley grain comprising a genetic variation which reduces the activityof SBEIIa by 40%, and a reduced level of SBEIIa and SBEIIb proteins inits endosperm, relative to barley grain of the Golden Promise variety,and starch comprising amylose, wherein the amylose content of the starchas measured by an iodometric method is at least 75% (w/w) of totalstarch content of the barley grain, b) optionally processing the barleygrain to produce milled, ground, pearled, rolled, kibbled or crackedgrain, flour, wholemeal or starch therefrom, and c) including the barleygrain of a), or the milled, ground, pearled, rolled, kibbled or crackedgrain, flour, wholemeal or starch of b) as an ingredient in the foodproduct, to thereby make the food product.
 15. A food product comprisingbarley grain which is wholegrain or milled, ground, pearled, rolled,kibbled or cracked grain, barley flour or barley wholemeal, wherein thebarley grain, barley flour or barley wholemeal comprises a geneticvariation which reduces the activity of SBEIIa by 40%, and a reducedlevel of SBEIIa and SBEIIb proteins in its endosperm, relative to barleygrain, barley flour or barley wholemeal, respectively, of the GoldenPromise variety of barley grain, and starch comprising amylose, whereinthe amylose content of the starch as measured by an iodometric method isat least 40% (w/w) of total starch content of the barley grain, barleyflour or barley wholemeal.
 16. The food product of claim 15, wherein thefood product is bread, cake, biscuits, noodles, quick soup or breakfastcereal.
 17. The process of claim 1, wherein the barley grain comprises6-8% (w/w) β-glucan as a percentage of total non-hulled grain weight.